diff --git a/.github/workflows/test-if.yml b/.github/workflows/test-if.yml
index 191e7c2..085851b 100644
--- a/.github/workflows/test-if.yml
+++ b/.github/workflows/test-if.yml
@@ -6,6 +6,7 @@ env:
   SOMETHING_TRUE: true
   SOMETHING_FALSE: false
   SOME_TEXT: text
+  ACT: true
 
 
 jobs:
@@ -389,3 +390,17 @@ jobs:
      - name: "Double checking expr: true && €{{ env.SOMETHING_FALSE == 'true' }}"
        if: steps.step57.conclusion == 'skipped'
        run: echo "true && ${{ env.SOMETHING_FALSE == 'true' }} should have been true, but wasn't"
+
+     - name: "✅ I should run, expr: €{{ env.ACT }}"
+       id: step60
+       if: ${{ env.ACT }}
+       run: echo OK
+
+     - name: "Double checking expr: €{{ env.ACT }}"
+       if: steps.step60.conclusion == 'skipped'
+       run: echo "${{ env.ACT }} should have been true, but wasn't"
+
+     - name: "❌ I should not run, expr: €{{ !env.ACT }}"
+       id: step61
+       if: ${{ !env.ACT }}
+       run: echo "${{ !env.ACT }} should be false, but was evaluated to true;" exit 1;
diff --git a/README.md b/README.md
index 5b44d58..026977f 100644
--- a/README.md
+++ b/README.md
@@ -166,6 +166,18 @@ Additionally, act supports loading environment variables from an `.env` file. Th
 act --env-file my.env
 ```
 
+# Skipping steps
+
+Act adds a special environement variable `ACT` that can be used to skip a step that you
+don't want to run locally. E.g. a step that posts a Slack message or bumps a version number.
+
+```yml
+- name: Some step
+  if: ${{ !env.ACT }}
+  run: |
+    ...
+```
+
 # Events
 
 Every [GitHub event](https://developer.github.com/v3/activity/events/types) is accompanied by a payload. You can provide these events in JSON format with the `--eventpath` to simulate specific GitHub events kicking off an action. For example:
diff --git a/pkg/runner/run_context.go b/pkg/runner/run_context.go
index 7a59a07..4615b28 100644
--- a/pkg/runner/run_context.go
+++ b/pkg/runner/run_context.go
@@ -47,6 +47,7 @@ func (rc *RunContext) GetEnv() map[string]string {
 	if rc.Env == nil {
 		rc.Env = mergeMaps(rc.Config.Env, rc.Run.Workflow.Env, rc.Run.Job().Env)
 	}
+	rc.Env["ACT"] = "true"
 	return rc.Env
 }
 
diff --git a/pkg/runner/run_context_test.go b/pkg/runner/run_context_test.go
index 07b27dd..fd9de7e 100644
--- a/pkg/runner/run_context_test.go
+++ b/pkg/runner/run_context_test.go
@@ -126,6 +126,9 @@ func TestRunContext_EvalBool(t *testing.T) {
 		// Check github context
 		{in: "github.actor == 'nektos/act'", out: true},
 		{in: "github.actor == 'unknown'", out: false},
+		// The special ACT flag
+		{in: "${{ env.ACT }}", out: true},
+		{in: "${{ !env.ACT }}", out: false},
 	}
 
 	updateTestIfWorkflow(t, tables, rc)