 <p>Since <code>selectedItem</code> is an observable, you need to invoke it for accessing/changing it's data.</p> <p>Try this:</p> <pre><code>&lt;input type="text" id="textBoxAddressLine1" name="textBoxAddressLine1Name" data-bind="value: selectedItem() ? selectedItem().AddressLine1 : ''" /&gt; </code></pre> <p>And in your ViewModel:</p> <pre><code>selectItem: function(data) { this.selectedItem(data); } </code></pre>