diff --git a/src/common/Elsa.Features/Services/IFeature.cs b/src/common/Elsa.Features/Services/IFeature.cs
index 78123e7e5..71c6ed504 100644
--- a/src/common/Elsa.Features/Services/IFeature.cs
+++ b/src/common/Elsa.Features/Services/IFeature.cs
@@ -1,8 +1,11 @@
+using JetBrains.Annotations;
+
 namespace Elsa.Features.Services;
 
 /// <summary>
 /// Represents a feature.
 /// </summary>
+[UsedImplicitly(ImplicitUseTargetFlags.WithInheritors | ImplicitUseTargetFlags.Members)]
 public interface IFeature
 {
     /// <summary>
diff --git a/src/modules/Elsa.Http/Abstractions/HttpCorrelationIdSelectorBase.cs b/src/modules/Elsa.Http/Abstractions/HttpCorrelationIdSelectorBase.cs
new file mode 100644
index 000000000..7403aef5c
--- /dev/null
+++ b/src/modules/Elsa.Http/Abstractions/HttpCorrelationIdSelectorBase.cs
@@ -0,0 +1,29 @@
+using Elsa.Http.Contracts;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Abstractions;
+
+/// <summary>
+/// Provides a base class for implementing <see cref="IHttpCorrelationIdSelector"/>.
+/// </summary>
+public abstract class HttpCorrelationIdSelectorBase : IHttpCorrelationIdSelector
+{
+    /// <inheritdoc />
+    public virtual double Priority => 0;
+
+    /// <summary>
+    /// Override this method to return the correlation ID for the specified HTTP context, or <c>null</c> if no correlation ID could be found.
+    /// </summary>
+    protected virtual ValueTask<string?> GetCorrelationIdAsync(HttpContext httpContext, CancellationToken cancellationToken = default)
+    {
+        var correlationId = GetCorrelationId(httpContext);
+        return new(correlationId);
+    }
+
+    /// <summary>
+    /// Override this method to return the correlation ID for the specified HTTP context, or <c>null</c> if no correlation ID could be found.
+    /// </summary>
+    protected virtual string? GetCorrelationId(HttpContext httpContext) => null;
+
+    ValueTask<string?> IHttpCorrelationIdSelector.GetCorrelationIdAsync(HttpContext httpContext, CancellationToken cancellationToken) => GetCorrelationIdAsync(httpContext, cancellationToken);
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Abstractions/HttpWorkflowInstanceIdSelectorBase.cs b/src/modules/Elsa.Http/Abstractions/HttpWorkflowInstanceIdSelectorBase.cs
new file mode 100644
index 000000000..6d70522fa
--- /dev/null
+++ b/src/modules/Elsa.Http/Abstractions/HttpWorkflowInstanceIdSelectorBase.cs
@@ -0,0 +1,29 @@
+using Elsa.Http.Contracts;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Abstractions;
+
+/// <summary>
+/// Provides a base class for implementing <see cref="IHttpCorrelationIdSelector"/>.
+/// </summary>
+public abstract class HttpWorkflowInstanceIdSelectorBase : IHttpWorkflowInstanceIdSelector
+{
+    /// <inheritdoc />
+    public virtual double Priority => 0;
+
+    /// <summary>
+    /// Override this method to return the workflow instance ID for the specified HTTP context, or <c>null</c> if no workflow instance ID could be found.
+    /// </summary>
+    protected virtual ValueTask<string?> GetWorkflowInstanceIdAsync(HttpContext httpContext, CancellationToken cancellationToken = default)
+    {
+        var workflowInstanceId = GetWorkflowInstanceId(httpContext);
+        return new(workflowInstanceId);
+    }
+
+    /// <summary>
+    /// Override this method to return the workflow instance ID for the specified HTTP context, or <c>null</c> if no workflow instance ID could be found.
+    /// </summary>
+    protected virtual string? GetWorkflowInstanceId(HttpContext httpContext) => null;
+
+    ValueTask<string?> IHttpWorkflowInstanceIdSelector.GetWorkflowInstanceIdAsync(HttpContext httpContext, CancellationToken cancellationToken) => GetWorkflowInstanceIdAsync(httpContext, cancellationToken);
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Contracts/IHttpCorrelationIdSelector.cs b/src/modules/Elsa.Http/Contracts/IHttpCorrelationIdSelector.cs
new file mode 100644
index 000000000..d663acd68
--- /dev/null
+++ b/src/modules/Elsa.Http/Contracts/IHttpCorrelationIdSelector.cs
@@ -0,0 +1,19 @@
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Contracts;
+
+/// <summary>
+/// Provides a way to select the correlation ID for a request.
+/// </summary>
+public interface IHttpCorrelationIdSelector
+{
+    /// <summary>
+    /// The priority of this selector. The selector with the highest priority will be used.
+    /// </summary>
+    double Priority { get; }
+    
+    /// <summary>
+    /// Returns the correlation ID for the specified HTTP context, or <c>null</c> if no correlation ID could be found.
+    /// </summary>
+    ValueTask<string?> GetCorrelationIdAsync(HttpContext httpContext, CancellationToken cancellationToken = default);
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Contracts/IHttpWorkflowInstanceIdSelector.cs b/src/modules/Elsa.Http/Contracts/IHttpWorkflowInstanceIdSelector.cs
new file mode 100644
index 000000000..28be3880f
--- /dev/null
+++ b/src/modules/Elsa.Http/Contracts/IHttpWorkflowInstanceIdSelector.cs
@@ -0,0 +1,19 @@
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Contracts;
+
+/// <summary>
+/// Provides a way to select the workflow instance ID for a request.
+/// </summary>
+public interface IHttpWorkflowInstanceIdSelector
+{
+    /// <summary>
+    /// The priority of this selector. The selector with the highest priority will be used.
+    /// </summary>
+    double Priority { get; }
+    
+    /// <summary>
+    /// Returns the workflow instance ID for the specified HTTP context, or <c>null</c> if no workflow instance ID could be found.
+    /// </summary>
+    ValueTask<string?> GetWorkflowInstanceIdAsync(HttpContext httpContext, CancellationToken cancellationToken = default);
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Elsa.Http.csproj b/src/modules/Elsa.Http/Elsa.Http.csproj
index 1ceceea66..d0cbfa09e 100644
--- a/src/modules/Elsa.Http/Elsa.Http.csproj
+++ b/src/modules/Elsa.Http/Elsa.Http.csproj
@@ -29,4 +29,6 @@
         <ProjectReference Include="..\Elsa.JavaScript\Elsa.JavaScript.csproj" />
     </ItemGroup>
 
+
+
 </Project>
diff --git a/src/modules/Elsa.Http/Extensions/ServiceCollectionExtensions.cs b/src/modules/Elsa.Http/Extensions/ServiceCollectionExtensions.cs
new file mode 100644
index 000000000..3218b25f0
--- /dev/null
+++ b/src/modules/Elsa.Http/Extensions/ServiceCollectionExtensions.cs
@@ -0,0 +1,31 @@
+using Elsa.Http.Contracts;
+using JetBrains.Annotations;
+using Microsoft.Extensions.DependencyInjection;
+
+// ReSharper disable once CheckNamespace
+namespace Elsa.Extensions;
+
+/// <summary>
+/// Contains extension methods for the <see cref="IServiceCollection"/> interface.
+/// </summary>
+[PublicAPI]
+public static class ServiceCollectionExtensions
+{
+    /// <summary>
+    /// Adds a <see cref="IHttpCorrelationIdSelector"/> implementation to the service collection.
+    /// </summary>
+    public static IServiceCollection AddHttpCorrelationIdSelector<T>(this IServiceCollection services) where T : class, IHttpCorrelationIdSelector
+    {
+        services.AddSingleton<IHttpCorrelationIdSelector, T>();
+        return services;
+    }
+    
+    /// <summary>
+    /// Adds a <see cref="IHttpCorrelationIdSelector"/> implementation to the service collection.
+    /// </summary>
+    public static IServiceCollection AddHttpCorrelationIdSelector(this IServiceCollection services, Func<IServiceProvider, IHttpCorrelationIdSelector> factory)
+    {
+        services.AddSingleton(factory);
+        return services;
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Features/HttpFeature.cs b/src/modules/Elsa.Http/Features/HttpFeature.cs
index e374ccc65..758be5462 100644
--- a/src/modules/Elsa.Http/Features/HttpFeature.cs
+++ b/src/modules/Elsa.Http/Features/HttpFeature.cs
@@ -12,6 +12,7 @@ using Elsa.Http.Options;
 using Elsa.Http.Parsers;
 using Elsa.Http.PortResolvers;
 using Elsa.Http.Providers;
+using Elsa.Http.Selectors;
 using Elsa.Http.Services;
 using Elsa.JavaScript.Features;
 using Elsa.Liquid.Features;
@@ -62,6 +63,24 @@ public class HttpFeature : FeatureBase
     /// </summary>
     public Action<IHttpClientBuilder> HttpClientBuilder { get; set; } = _ => { };
 
+    /// <summary>
+    /// A list of <see cref="IHttpCorrelationIdSelector"/> types to register with the service collection.
+    /// </summary>
+    public ICollection<Type> HttpCorrelationIdSelectorTypes { get; } = new List<Type>
+    {
+        typeof(HeaderHttpCorrelationIdSelector), 
+        typeof(QueryStringHttpCorrelationIdSelector)
+    };
+
+    /// <summary>
+    /// A list of <see cref="IHttpWorkflowInstanceIdSelector"/> types to register with the service collection.
+    /// </summary>
+    public ICollection<Type> HttpWorkflowInstanceIdSelectorTypes { get; } = new List<Type>
+    {
+        typeof(HeaderHttpWorkflowInstanceIdSelector), 
+        typeof(QueryStringHttpWorkflowInstanceIdSelector)
+    };
+
     /// <inheritdoc />
     public override void Configure()
     {
@@ -78,7 +97,7 @@ public class HttpFeature : FeatureBase
 
             management.AddActivitiesFrom<HttpFeature>();
         });
-        
+
         Services.AddRequestHandler<ValidateWorkflowRequestHandler, ValidateWorkflowRequest, ValidateWorkflowResponse>();
     }
 
@@ -141,5 +160,12 @@ public class HttpFeature : FeatureBase
             // AuthenticationBasedHttpEndpointAuthorizationHandler requires Authorization services.
             // We could consider creating a separate module for installing authorization services.
             .AddAuthorization();
+        
+        // Add selectors.
+        foreach (var httpCorrelationIdSelectorType in HttpCorrelationIdSelectorTypes) 
+            Services.AddSingleton(typeof(IHttpCorrelationIdSelector), httpCorrelationIdSelectorType);
+        
+        foreach (var httpWorkflowInstanceIdSelectorType in HttpWorkflowInstanceIdSelectorTypes)
+            Services.AddSingleton(typeof(IHttpWorkflowInstanceIdSelector), httpWorkflowInstanceIdSelectorType);
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Middleware/WorkflowsMiddleware.cs b/src/modules/Elsa.Http/Middleware/WorkflowsMiddleware.cs
index 0b1302341..b0d04a92f 100644
--- a/src/modules/Elsa.Http/Middleware/WorkflowsMiddleware.cs
+++ b/src/modules/Elsa.Http/Middleware/WorkflowsMiddleware.cs
@@ -27,6 +27,8 @@ public class WorkflowsMiddleware
     private readonly IWorkflowRuntime _workflowRuntime;
     private readonly IRouteMatcher _routeMatcher;
     private readonly IRouteTable _routeTable;
+    private readonly IEnumerable<IHttpCorrelationIdSelector> _correlationIdSelectors;
+    private readonly IEnumerable<IHttpWorkflowInstanceIdSelector> _workflowInstanceIdSelectors;
     private readonly IHttpBookmarkProcessor _httpBookmarkProcessor;
     private readonly IHttpEndpointWorkflowFaultHandler _httpEndpointWorkflowFaultHandler;
     private readonly IHttpEndpointAuthorizationHandler _httpEndpointAuthorizationHandler;
@@ -52,7 +54,9 @@ public class WorkflowsMiddleware
         IBookmarkHasher hasher,
         IBookmarkPayloadSerializer serializer,
         IRouteMatcher routeMatcher,
-        IRouteTable routeTable)
+        IRouteTable routeTable,
+        IEnumerable<IHttpCorrelationIdSelector> correlationIdSelectors,
+        IEnumerable<IHttpWorkflowInstanceIdSelector> workflowInstanceIdSelectors)
     {
         _next = next;
         _workflowRuntime = workflowRuntime;
@@ -66,6 +70,8 @@ public class WorkflowsMiddleware
         _serializer = serializer;
         _routeMatcher = routeMatcher;
         _routeTable = routeTable;
+        _correlationIdSelectors = correlationIdSelectors;
+        _workflowInstanceIdSelectors = workflowInstanceIdSelectors;
     }
 
     /// <summary>
@@ -97,14 +103,13 @@ public class WorkflowsMiddleware
             [HttpEndpoint.RequestPathInputKey] = path
         };
 
-        // TODO: Get correlation ID from query string or header.
-        var correlationId = default(string);
-
-        var request = httpContext.Request;
-        var method = request.Method!.ToLowerInvariant();
-        var bookmarkPayload = new HttpEndpointBookmarkPayload(matchingPath, method);
-        var triggerOptions = new TriggerWorkflowsRuntimeOptions(correlationId, default, default, input);
         var cancellationToken = httpContext.RequestAborted;
+        var request = httpContext.Request;
+        var method = request.Method.ToLowerInvariant();
+        var correlationId = await GetCorrelationIdAsync(httpContext, httpContext.RequestAborted);
+        var workflowInstanceId = await GetWorkflowInstanceIdAsync(httpContext, httpContext.RequestAborted);
+        var bookmarkPayload = new HttpEndpointBookmarkPayload(matchingPath, method);
+        var triggerOptions = new TriggerWorkflowsRuntimeOptions(correlationId, workflowInstanceId, default, input);
         var workflowsFilter = new WorkflowsFilter(_activityTypeName, bookmarkPayload, triggerOptions);
         var workflowMatches = (await _workflowRuntime.FindWorkflowsAsync(workflowsFilter, cancellationToken)).ToList();
 
@@ -146,6 +151,36 @@ public class WorkflowsMiddleware
         return routeTemplate;
     }
 
+    private async Task<string?> GetCorrelationIdAsync(HttpContext httpContext, CancellationToken cancellationToken)
+    {
+        var correlationId = default(string);
+
+        foreach (var selector in _correlationIdSelectors.OrderByDescending(x => x.Priority))
+        {
+            correlationId = await selector.GetCorrelationIdAsync(httpContext, cancellationToken);
+
+            if (correlationId != null)
+                break;
+        }
+
+        return correlationId;
+    }
+
+    private async Task<string?> GetWorkflowInstanceIdAsync(HttpContext httpContext, CancellationToken cancellationToken)
+    {
+        var workflowInstanceId = default(string);
+
+        foreach (var selector in _workflowInstanceIdSelectors.OrderByDescending(x => x.Priority))
+        {
+            workflowInstanceId = await selector.GetWorkflowInstanceIdAsync(httpContext, cancellationToken);
+
+            if (workflowInstanceId != null)
+                break;
+        }
+
+        return workflowInstanceId;
+    }
+
     private static async Task WriteResponseAsync(HttpContext httpContext, CancellationToken cancellationToken)
     {
         var response = httpContext.Response;
diff --git a/src/modules/Elsa.Http/Selectors/HeaderHttpCorrelationIdSelector.cs b/src/modules/Elsa.Http/Selectors/HeaderHttpCorrelationIdSelector.cs
new file mode 100644
index 000000000..0757f9ab3
--- /dev/null
+++ b/src/modules/Elsa.Http/Selectors/HeaderHttpCorrelationIdSelector.cs
@@ -0,0 +1,16 @@
+using Elsa.Http.Abstractions;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Selectors;
+
+/// <summary>
+/// Returns the correlation ID from the <c>X-Correlation-ID</c> header, if any.
+/// </summary>
+public class HeaderHttpCorrelationIdSelector : HttpCorrelationIdSelectorBase
+{
+    /// <inheritdoc />
+    protected override string? GetCorrelationId(HttpContext httpContext)
+    {
+        return httpContext.Request.Headers["X-Correlation-ID"].FirstOrDefault();
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Selectors/HeaderHttpWorkflowInstanceIdSelector.cs b/src/modules/Elsa.Http/Selectors/HeaderHttpWorkflowInstanceIdSelector.cs
new file mode 100644
index 000000000..7294d7081
--- /dev/null
+++ b/src/modules/Elsa.Http/Selectors/HeaderHttpWorkflowInstanceIdSelector.cs
@@ -0,0 +1,16 @@
+using Elsa.Http.Abstractions;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Selectors;
+
+/// <summary>
+/// Returns the workflow instance ID from the <c>X-Workflow-Instance-ID</c> header, if any.
+/// </summary>
+public class HeaderHttpWorkflowInstanceIdSelector : HttpWorkflowInstanceIdSelectorBase
+{
+    /// <inheritdoc />
+    protected override string? GetWorkflowInstanceId(HttpContext httpContext)
+    {
+        return httpContext.Request.Headers["X-Workflow-Instance-ID"].FirstOrDefault();
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Selectors/QueryStringHttpCorrelationIdSelector.cs b/src/modules/Elsa.Http/Selectors/QueryStringHttpCorrelationIdSelector.cs
new file mode 100644
index 000000000..8c632bbb4
--- /dev/null
+++ b/src/modules/Elsa.Http/Selectors/QueryStringHttpCorrelationIdSelector.cs
@@ -0,0 +1,16 @@
+using Elsa.Http.Abstractions;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Selectors;
+
+/// <summary>
+/// Returns the correlation ID from the <c>correlationId</c> query string parameter.
+/// </summary>
+public class QueryStringHttpCorrelationIdSelector : HttpCorrelationIdSelectorBase
+{
+    /// <inheritdoc />
+    protected override string? GetCorrelationId(HttpContext httpContext)
+    {
+        return httpContext.Request.Query["correlationId"].FirstOrDefault();
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Selectors/QueryStringHttpWorkflowInstanceIdSelector.cs b/src/modules/Elsa.Http/Selectors/QueryStringHttpWorkflowInstanceIdSelector.cs
new file mode 100644
index 000000000..32ade85cc
--- /dev/null
+++ b/src/modules/Elsa.Http/Selectors/QueryStringHttpWorkflowInstanceIdSelector.cs
@@ -0,0 +1,16 @@
+using Elsa.Http.Abstractions;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Http.Selectors;
+
+/// <summary>
+/// Returns the workflow instance ID from the <c>X-Workflow-Instance-ID</c> header, if any.
+/// </summary>
+public class QueryStringHttpWorkflowInstanceIdSelector : HttpWorkflowInstanceIdSelectorBase
+{
+    /// <inheritdoc />
+    protected override string? GetWorkflowInstanceId(HttpContext httpContext)
+    {
+        return httpContext.Request.Query["workflowInstanceId"].FirstOrDefault();
+    }
+}
\ No newline at end of file