radio is not SELECTED, how to set "selected"? <p>One of my radio should selected when initialize (first load then user can change the selection), but radio is not selected first time, how to initialize "Selected" appropriately?</p> <p><strong>Here radio "Two" should selected as "selected" is True for this?</strong></p> <pre><code>@using (Html.BeginForm("Index", "Two", FormMethod.Post, new Dictionary&lt;string, object&gt; { { "data-bind", "submit:onSubmit" } })) { &lt;table&gt; &lt;tr&gt; &lt;td&gt; &lt;div data-bind="foreach: items"&gt; &lt;input type="radio" name="items" data-bind="attr: { value: id }, checked: $root.selected" /&gt; &lt;span data-bind="text: name"&gt;&lt;/span&gt; &lt;/div&gt; &lt;div data-bind="text: selected"&gt; &lt;/div&gt; &lt;/td&gt; &lt;/tr&gt; &lt;/table&gt; &lt;input type="submit" name="send" value="Send" /&gt; } &lt;script type="text/javascript"&gt; var viewModel = { items: [ { "id": 1, "name": "one", "selected": false }, { "id": 2, "name": "two", "selected": true }, { "id": 3, "name": "three", "selected": false } ], selected: ko.observable(), onSubmit: function(){ var x = this.selected(); } }; $(function() { ko.applyBindings(viewModel); }); &lt;/script&gt; </code></pre>