diff --git a/README.md b/README.md
index 2259eeb7c..d6e05a342 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ shall be implemented.
 Documentation: <https://shopify.github.io/liquid/basics/introduction/#tags>
 
 - [x] [assign](https://shopify.github.io/liquid/tags/control-flow/)
-- [ ] [case/when](https://shopify.github.io/liquid/tags/control-flow/)
+- [x] [case/when](https://shopify.github.io/liquid/tags/control-flow/)
 - [ ] [if](https://shopify.github.io/liquid/tags/control-flow/)
 - [ ] [unless](https://shopify.github.io/liquid/tags/control-flow/)
 - [ ] [elsif/else](https://shopify.github.io/liquid/tags/control-flow/)
diff --git a/filter.js b/filter.js
index 59359dddd..f670e9152 100644
--- a/filter.js
+++ b/filter.js
@@ -12,7 +12,7 @@ var _filterInstance = {
 module.exports = function() {
     var filters = {};
 
-    function parse(str) {
+    function construct(str) {
         var match = lexical.patterns.filterLine.exec(str.trim());
         if (!match) {
             throw new Error('illegal filter: ' + str);
@@ -43,6 +43,6 @@ module.exports = function() {
     }
 
     return {
-        parse, register, clear
+        construct, register, clear
     };
 };
diff --git a/index.js b/index.js
index a1fcd96b8..fea1487f1 100644
--- a/index.js
+++ b/index.js
@@ -24,11 +24,12 @@ function factory(){
     engine.tag = Tag();
     engine.filter = Filter();
 
-    var render = Render(engine.filter, engine.tag);
+    var renderer = Render(engine.filter, engine.tag);
+    engine.evaluate = renderer.evaluate;
+    engine.renderTokens = renderer.render;
     engine.render = function(html, ctx) {
-        return render.render(tokenizer.parse(html), context.factory(ctx));
+        return engine.renderTokens(tokenizer.parse(html), context.factory(ctx));
     },
-    engine.evaluate = render.evaluate;
 
     fs.readdirSync(tagsPath).map(function(f){
         var match = /^(\w+)\.js$/.exec(f);
diff --git a/lexical.js b/lexical.js
index 613be6bf5..85f9f7bbd 100644
--- a/lexical.js
+++ b/lexical.js
@@ -25,7 +25,7 @@ var rangeLine = new RegExp(`^(?:${range.source})$`);
 var filterLine = new RegExp(`^(?:${filter.source})$`);
 
 exports.patterns = {
-    quoted, number, bool, range, literal, hash, filter, identifier,
+    quoted, number, bool, range, literal, hash, filter, identifier, value,
     quotedLine, numberLine, boolLine, rangeLine, literalLine, filterLine
 };
 
diff --git a/render.js b/render.js
index 29e1b6ff2..6850ac86d 100644
--- a/render.js
+++ b/render.js
@@ -21,22 +21,23 @@ module.exports = function(Filter, Tag) {
     }
 
     function evaluate(str, ctx) {
+        if(!ctx) throw new Error('ctx is needed to evaluate');
         var filters = str.split('|');
         var val = ctx.get(filters.shift());
         return filters
-            .map(str => Filter.parse(str))
+            .map(str => Filter.construct(str))
             .reduce((v, filter) => filter.render(v, ctx), val);
     }
 
     function renderTag(token, tokens, ctx) {
-        var tag = Tag.parse(token.value),
+        var tag = Tag.construct(token),
             subTokens = [];
         if (tag.needClose) {
             var curToken, endToken = 'end' + tag.name;
-            while ((curToken = tokens.shift()).value !== endToken) {
+            while ((curToken = tokens.shift()) && curToken.value !== endToken) {
                 subTokens.push(curToken);
             }
-            if (curToken.value !== endToken) {
+            if (!curToken) {
                 throw new Error(`${token.value} not closed`);
             }
         }
diff --git a/tag.js b/tag.js
index 9d356c355..9edcba0b8 100644
--- a/tag.js
+++ b/tag.js
@@ -30,22 +30,15 @@ module.exports = function() {
         tags[name] = tag;
     }
 
-    function parse(str) {
-        var match = lexical.patterns.identifier.exec(str.trim());
-        if (!match) throw new Error('illegal tag: ' + str);
-
-        var tagInstance = factory(match[0], str);
-        return tagInstance;
-    }
-
-    function factory(name, markup) {
-        var tag = tags[name];
-        if (!tag) throw new Error(`tag ${name} not found`);
+    function construct(token) {
+        var tag = tags[token.name];
+        if (!tag) throw new Error(`tag ${token.name} not found`);
 
         var instance = Object.create(_tagInstance);
-        instance.name = name;
-        instance.markup = markup;
+        instance.name = token.name;
+        instance.markup = token.value;
         instance.tag = tag;
+        instance.needClose = tag.needClose;
         return instance;
     }
 
@@ -54,6 +47,6 @@ module.exports = function() {
     }
 
     return {
-        parse, register, hash, clear
+        construct, register, hash, clear
     };
 };
diff --git a/tags/case.js b/tags/case.js
new file mode 100644
index 000000000..0f8bdd1c8
--- /dev/null
+++ b/tags/case.js
@@ -0,0 +1,34 @@
+var Liquid = require('..');
+var patterns = Liquid.lexical.patterns;
+var caseRE = new RegExp(`^\\s*case\\s+(${patterns.value.source})`);
+var whenRE = new RegExp(`^\\s*when\\s+(${patterns.value.source})`);
+
+module.exports = function(liquid) {
+
+    liquid.registerTag('case', {
+        needClose: true,
+        render: function(tokens, ctx, markup, hash) {
+            var match = markup.match(caseRE);
+            var cond = liquid.evaluate(match[1], ctx);
+
+            var partialTokens = [],
+                matching = false;
+            for (var i = 0; i < tokens.length; i++) {
+                var token = tokens[i];
+                if (token.type === 'tag' && token.name === 'when') {
+                    if (matching) break;
+                    match = token.value.match(whenRE);
+                    if(!match) continue;
+
+                    var val = liquid.evaluate(match[1], ctx);
+                    if (val === cond) matching = true;
+                } else if (token.type === 'tag' && token.name === 'else') {
+                    if (matching) break;
+                    else matching = true;
+                } else if (matching) partialTokens.push(token);
+            }
+
+            return liquid.renderTokens(partialTokens, ctx);
+        }
+    });
+};
diff --git a/test/filter.js b/test/filter.js
index e79433dee..1e6fb1839 100644
--- a/test/filter.js
+++ b/test/filter.js
@@ -16,19 +16,19 @@ describe('filter', function() {
     });
     it('should throw when not registered', function() {
         expect(function() {
-            filter.parse('foo');
+            filter.construct('foo');
         }).to.throw(/filter foo not found/);
     });
 
     it('should register a simple filter', function(){
         filter.register('foo', x => x.toUpperCase());
-        expect(filter.parse('foo').render('foo', ctx)).to.equal('FOO');
+        expect(filter.construct('foo').render('foo', ctx)).to.equal('FOO');
     });
 
     it('should call filter with corrct arguments', function(){
         var spy = sinon.spy();
         filter.register('foo', spy);
-        filter.parse('foo: 33').render('foo', ctx);
+        filter.construct('foo: 33').render('foo', ctx);
         expect(spy).to.have.been.calledWith('foo', 33);
     });
 });
diff --git a/test/render.js b/test/render.js
index 94b023480..eebd1850d 100644
--- a/test/render.js
+++ b/test/render.js
@@ -22,7 +22,8 @@ describe('render', function() {
         });
         tagToken = {
             type: 'tag',
-            value: 'foo bar:x foo:"FOO" num:2.3'
+            value: 'foo bar:x foo:"FOO" num:2.3',
+            name: 'foo'
         };
         htmlToken = {
             type: 'html',
diff --git a/test/tag.js b/test/tag.js
index a56057b43..c7e83189c 100644
--- a/test/tag.js
+++ b/test/tag.js
@@ -9,7 +9,7 @@ var context = require('../context.js');
 
 describe('tag', function() {
     var ctx;
-    before(function(){
+    before(function() {
         ctx = context.factory({
             foo: 'bar',
             arr: [2, 1]
@@ -19,7 +19,11 @@ describe('tag', function() {
 
     it('should throw when not registered', function() {
         expect(function() {
-            tag.parse('foo');
+            tag.construct({
+                type: 'tag',
+                value: 'foo',
+                name: 'foo'
+            });
         }).to.throw(/tag foo not found/);
     });
 
@@ -44,7 +48,11 @@ describe('tag', function() {
         tag.register('foo', {
             render: spy
         });
-        tag.parse('foo').render(tokens, ctx);
+        tag.construct({
+            type: 'tag',
+            value: 'foo',
+            name: 'foo'
+        }).render(tokens, ctx);
         expect(spy).to.have.been.called;
     });
 
@@ -54,7 +62,11 @@ describe('tag', function() {
         tag.register('foo', {
             render: spy
         });
-        var t = tag.parse('foo aa:foo bb: arr[0] cc: 2.3');
+        var t = tag.construct({
+            type: 'tag',
+            value: 'foo aa:foo bb: arr[0] cc: 2.3',
+            name: 'foo'
+        });
         t.render(tokens, ctx);
         expect(spy).to.have.been.calledWithMatch(tokens, ctx, 'foo', {
             aa: 'bar',
diff --git a/test/tags.js b/test/tags.js
index e8ec39aac..8aeae51c6 100644
--- a/test/tags.js
+++ b/test/tags.js
@@ -4,16 +4,31 @@ const expect = chai.expect;
 var liquid = require('..')();
 
 var ctx = {
+    empty: '',
     foo: 'bar',
     arr: [-2, 'a']
 };
 
 describe('tags', function() {
     it('should support assign', function() {
-        test('{% assign foo="bar"%}{{foo}}', 'bar');
+        expect(liquid.render('{% assign foo="bar"%}{{foo}}', ctx)).to.equal('bar');
+    });
+    it('should support case', function() {
+        expect(function() {
+            liquid.render('{% case "foo"%}');
+        }).to.throw(/case "foo" not closed/);
+        expect(liquid.render('{% case "foo"%}' +
+            '{% when "foo" %}foo{% when "bar"%}bar' +
+            '{%endcase%}', ctx)).to.equal('foo');
+        expect(liquid.render('{% case empty %}' +
+            '{% when "foo" %}foo{% when ""%}bar' +
+            '{%endcase%}')).to.equal('bar');
+        expect(liquid.render('{% case false %}' +
+            '{% when "foo" %}foo{% when ""%}bar' +
+            '{%endcase%}')).to.equal('');
+        expect(liquid.render('{% case "a" %}' +
+            '{% when "b" %}b{% when "c"%}c{%else %}d' +
+            '{%endcase%}')).to.equal('d');
     });
 });
 
-function test(src, dst){
-    expect(liquid.render(src, ctx)).to.equal(dst);
-}
diff --git a/tokenizer.js b/tokenizer.js
index e4ea0e013..350cbbe61 100644
--- a/tokenizer.js
+++ b/tokenizer.js
@@ -1,3 +1,4 @@
+const lexical = require('./lexical.js');
 
 function parse(html){
     var tokens = [];
@@ -12,21 +13,21 @@ function parse(html){
             htmlFragment = html.slice(idx, result.index);
             tokens.push({
                 type: 'html',
-                raw: htmlFragment,
                 value: htmlFragment
             });
         }
         if(result[1]){
+            var match = result[1].trim().match(lexical.patterns.identifier);
+            if (!match) throw new Error('illegal tag: ' + result[1]);
             tokens.push({
                 type: 'tag',
-                raw: result[1],
+                name: match[0],
                 value: result[2].trim()
             });
         }
         else{
             tokens.push({
                 type: 'output',
-                raw: result[3],
                 value: result[4].trim()
             });
         }
@@ -37,7 +38,6 @@ function parse(html){
         htmlFragment = html.slice(idx, html.length);
         tokens.push({
             type: 'html',
-            raw: htmlFragment,
             value: htmlFragment
         });
     }