diff --git a/orgs.go b/orgs.go
index a128e4c..aaf1e74 100644
--- a/orgs.go
+++ b/orgs.go
@@ -65,6 +65,19 @@ func (s *OrgService) RemoveMember(ctx context.Context, org, username string) err
 	return s.client.Delete(ctx, path)
 }
 
+// IsMember reports whether a user is a member of an organisation.
+func (s *OrgService) IsMember(ctx context.Context, org, username string) (bool, error) {
+	path := ResolvePath("/api/v1/orgs/{org}/members/{username}", pathParams("org", org, "username", username))
+	resp, err := s.client.doJSON(ctx, http.MethodGet, path, nil, nil)
+	if err != nil {
+		if IsNotFound(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	return resp.StatusCode == http.StatusNoContent, nil
+}
+
 // ListBlockedUsers returns all users blocked by an organisation.
 func (s *OrgService) ListBlockedUsers(ctx context.Context, org string) ([]types.User, error) {
 	path := ResolvePath("/api/v1/orgs/{org}/blocks", pathParams("org", org))
diff --git a/orgs_test.go b/orgs_test.go
index 08a36ca..94bb985 100644
--- a/orgs_test.go
+++ b/orgs_test.go
@@ -88,6 +88,28 @@ func TestOrgService_ListMembers_Good(t *testing.T) {
 	}
 }
 
+func TestOrgService_IsMember_Good(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			t.Errorf("expected GET, got %s", r.Method)
+		}
+		if r.URL.Path != "/api/v1/orgs/core/members/alice" {
+			t.Errorf("wrong path: %s", r.URL.Path)
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}))
+	defer srv.Close()
+
+	f := NewForge(srv.URL, "tok")
+	member, err := f.Orgs.IsMember(context.Background(), "core", "alice")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !member {
+		t.Fatal("got member=false, want true")
+	}
+}
+
 func TestOrgService_ListPublicMembers_Good(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodGet {