diff --git a/index.html b/index.html
index 87e93c643..07063cf81 100644
--- a/index.html
+++ b/index.html
@@ -81,6 +81,7 @@
         <script src="js/id/actions/delete_relation.js"></script>
         <script src="js/id/actions/delete_way.js"></script>
         <script src='js/id/actions/disconnect.js'></script>
+        <script src='js/id/actions/join.js'></script>
         <script src='js/id/actions/move_node.js'></script>
         <script src='js/id/actions/move_way.js'></script>
         <script src='js/id/actions/circularize.js'></script>
diff --git a/js/id/actions/join.js b/js/id/actions/join.js
new file mode 100644
index 000000000..fd6862a9b
--- /dev/null
+++ b/js/id/actions/join.js
@@ -0,0 +1,65 @@
+// Join ways at the end node they share.
+//
+// This is the inverse of `iD.actions.Split`.
+//
+// Reference:
+//   https://github.com/systemed/potlatch2/blob/master/net/systemeD/halcyon/connection/actions/MergeWaysAction.as
+//   https://github.com/openstreetmap/josm/blob/mirror/src/org/openstreetmap/josm/actions/CombineWayAction.java
+//
+iD.actions.Join = function(idA, idB) {
+    var action = function(graph) {
+        var a = graph.entity(idA),
+            b = graph.entity(idB),
+            nodes, tags;
+
+        if (a.first() === b.first()) {
+            // a <-- b ==> c
+            // Expected result:
+            // a <-- b <-- c
+            nodes = b.nodes.slice().reverse().concat(a.nodes.slice(1));
+
+        } else if (a.first() === b.last()) {
+            // a <-- b <== c
+            // Expected result:
+            // a <-- b <-- c
+            nodes = b.nodes.concat(a.nodes.slice(1));
+
+        } else if (a.last()  === b.first()) {
+            // a --> b ==> c
+            // Expected result:
+            // a --> b --> c
+            nodes = a.nodes.concat(b.nodes.slice(1));
+
+        } else if (a.last()  === b.last()) {
+            // a --> b <== c
+            // Expected result:
+            // a --> b --> c
+            nodes = a.nodes.concat(b.nodes.slice().reverse().slice(1));
+        }
+
+        graph.parentRelations(b)
+            .forEach(function (parent) {
+                var memberA = parent.memberById(idA),
+                    memberB = parent.memberById(idB);
+                if (!memberA) {
+                    graph = graph.replace(parent.addMember({id: idA, role: memberB.role}));
+                }
+            });
+
+        graph = graph.replace(a.mergeTags(b.tags).update({nodes: nodes}));
+        graph = iD.actions.DeleteWay(idB)(graph);
+
+        return graph;
+    };
+
+    action.enabled = function(graph) {
+        var a = graph.entity(idA),
+            b = graph.entity(idB);
+        return a.first() === b.first() ||
+               a.first() === b.last()  ||
+               a.last()  === b.first() ||
+               a.last()  === b.last();
+    };
+
+    return action;
+};
diff --git a/js/id/actions/split.js b/js/id/actions/split.js
index 0c648bd26..19a71c619 100644
--- a/js/id/actions/split.js
+++ b/js/id/actions/split.js
@@ -1,5 +1,7 @@
 // Split a way at the given node.
 //
+// This is the inverse of `iD.actions.Join`.
+//
 // For testing convenience, accepts an ID to assign to the new way.
 // Normally, this will be undefined and the way will automatically
 // be assigned a new ID.
diff --git a/test/index.html b/test/index.html
index 512a1ee1e..524894c36 100644
--- a/test/index.html
+++ b/test/index.html
@@ -78,6 +78,7 @@
     <script src="../js/id/actions/delete_relation.js"></script>
     <script src="../js/id/actions/delete_way.js"></script>
     <script src='../js/id/actions/disconnect.js'></script>
+    <script src='../js/id/actions/join.js'></script>
     <script src='../js/id/actions/move_node.js'></script>
     <script src='../js/id/actions/move_way.js'></script>
     <script src='../js/id/actions/noop.js'></script>
@@ -147,6 +148,7 @@
     <script src="spec/actions/delete_relation.js"></script>
     <script src="spec/actions/delete_way.js"></script>
     <script src='spec/actions/disconnect.js'></script>
+    <script src="spec/actions/join.js"></script>
     <script src="spec/actions/move_node.js"></script>
     <script src="spec/actions/move_way.js"></script>
     <script src="spec/actions/noop.js"></script>
diff --git a/test/index_packaged.html b/test/index_packaged.html
index 5adaf06f6..948ed0ae1 100644
--- a/test/index_packaged.html
+++ b/test/index_packaged.html
@@ -40,6 +40,7 @@
     <script src="spec/actions/delete_relation.js"></script>
     <script src="spec/actions/delete_way.js"></script>
     <script src='spec/actions/disconnect.js'></script>
+    <script src="spec/actions/join.js"></script>
     <script src="spec/actions/move_node.js"></script>
     <script src="spec/actions/move_way.js"></script>
     <script src="spec/actions/noop.js"></script>
diff --git a/test/spec/actions/join.js b/test/spec/actions/join.js
new file mode 100644
index 000000000..1cddb94bf
--- /dev/null
+++ b/test/spec/actions/join.js
@@ -0,0 +1,172 @@
+describe("iD.actions.Join", function () {
+    describe("#enabled", function () {
+        it("returns true for ways that share an end/start node", function () {
+            // a --> b ==> c
+            var graph = iD.Graph({
+                    'a': iD.Node({id: 'a'}),
+                    'b': iD.Node({id: 'b'}),
+                    'c': iD.Node({id: 'c'}),
+                    '-': iD.Way({id: '-', nodes: ['a', 'b']}),
+                    '=': iD.Way({id: '=', nodes: ['b', 'c']})
+                });
+
+            expect(iD.actions.Join('-', '=').enabled(graph)).to.be.true;
+        });
+
+        it("returns true for ways that share a start/end node", function () {
+            // a <-- b <== c
+            var graph = iD.Graph({
+                    'a': iD.Node({id: 'a'}),
+                    'b': iD.Node({id: 'b'}),
+                    'c': iD.Node({id: 'c'}),
+                    '-': iD.Way({id: '-', nodes: ['b', 'a']}),
+                    '=': iD.Way({id: '=', nodes: ['c', 'b']})
+                });
+
+            expect(iD.actions.Join('-', '=').enabled(graph)).to.be.true;
+        });
+
+        it("returns true for ways that share a start/start node", function () {
+            // a <-- b ==> c
+            var graph = iD.Graph({
+                    'a': iD.Node({id: 'a'}),
+                    'b': iD.Node({id: 'b'}),
+                    'c': iD.Node({id: 'c'}),
+                    '-': iD.Way({id: '-', nodes: ['b', 'a']}),
+                    '=': iD.Way({id: '=', nodes: ['b', 'c']})
+                });
+
+            expect(iD.actions.Join('-', '=').enabled(graph)).to.be.true;
+        });
+
+        it("returns true for ways that share an end/end node", function () {
+            // a --> b <== c
+            var graph = iD.Graph({
+                    'a': iD.Node({id: 'a'}),
+                    'b': iD.Node({id: 'b'}),
+                    'c': iD.Node({id: 'c'}),
+                    '-': iD.Way({id: '-', nodes: ['a', 'b']}),
+                    '=': iD.Way({id: '=', nodes: ['c', 'b']})
+                });
+
+            expect(iD.actions.Join('-', '=').enabled(graph)).to.be.true;
+        });
+
+        it("returns false for ways that don't share the necessary nodes", function () {
+            // a -- b -- c
+            //      |
+            //      d
+            var graph = iD.Graph({
+                    'a': iD.Node({id: 'a'}),
+                    'b': iD.Node({id: 'b'}),
+                    'c': iD.Node({id: 'c'}),
+                    'd': iD.Node({id: 'd'}),
+                    '-': iD.Way({id: '-', nodes: ['a', 'b', 'c']}),
+                    '=': iD.Way({id: '=', nodes: ['b', 'd']})
+                });
+
+            expect(iD.actions.Join('-', '=').enabled(graph)).to.be.false;
+        });
+    });
+
+    it("joins a --> b ==> c", function () {
+        // Expected result:
+        // a --> b --> c
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['a', 'b']}),
+                '=': iD.Way({id: '=', nodes: ['b', 'c']})
+            });
+
+        graph = iD.actions.Join('-', '=')(graph);
+
+        expect(graph.entity('-').nodes).to.eql(['a', 'b', 'c']);
+        expect(graph.entity('=')).to.be.undefined;
+    });
+
+    it("joins a <-- b <== c", function () {
+        // Expected result:
+        // a <-- b <-- c
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['b', 'a']}),
+                '=': iD.Way({id: '=', nodes: ['c', 'b']})
+            });
+
+        graph = iD.actions.Join('-', '=')(graph);
+
+        expect(graph.entity('-').nodes).to.eql(['c', 'b', 'a']);
+        expect(graph.entity('=')).to.be.undefined;
+    });
+
+    it("joins a <-- b ==> c", function () {
+        // Expected result:
+        // a <-- b <-- c
+        // tags on === reversed
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['b', 'a']}),
+                '=': iD.Way({id: '=', nodes: ['b', 'c']})
+            });
+
+        graph = iD.actions.Join('-', '=')(graph);
+
+        expect(graph.entity('-').nodes).to.eql(['c', 'b', 'a']);
+        expect(graph.entity('=')).to.be.undefined;
+    });
+
+    it("joins a --> b <== c", function () {
+        // Expected result:
+        // a --> b --> c
+        // tags on === reversed
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['a', 'b']}),
+                '=': iD.Way({id: '=', nodes: ['c', 'b']})
+            });
+
+        graph = iD.actions.Join('-', '=')(graph);
+
+        expect(graph.entity('-').nodes).to.eql(['a', 'b', 'c']);
+        expect(graph.entity('=')).to.be.undefined;
+    });
+
+    it("merges tags", function () {
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['a', 'b'], tags: {a: 'a', b: '-', c: 'c'}}),
+                '=': iD.Way({id: '=', nodes: ['b', 'c'], tags: {a: 'a', b: '=', d: 'd'}})
+            });
+
+        graph = iD.actions.Join('-', '=')(graph);
+
+        expect(graph.entity('-').tags).to.eql({a: 'a', b: '-; =', c: 'c', d: 'd'});
+    });
+
+    it("merges relations", function () {
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['a', 'b']}),
+                '=': iD.Way({id: '=', nodes: ['b', 'c']}),
+                'r1': iD.Relation({id: 'r1', members: [{id: '=', role: 'r1'}]}),
+                'r2': iD.Relation({id: 'r2', members: [{id: '=', role: 'r1'}, {id: '-', role: 'r2'}]})
+            });
+
+        graph = iD.actions.Join('-', '=')(graph);
+
+        expect(graph.entity('r1').members).to.eql([{id: '-', role: 'r1'}]);
+        expect(graph.entity('r2').members).to.eql([{id: '-', role: 'r2'}]);
+    });
+});