The ClientImageLoaded client-side event doesn't fire for the first loaded image when DisplayAreaMode="Image". The issue can be reproduced for the following configuration: <telerik:RadImageGallery runat="server" Width="600px" Height="480px" DisplayAreaMode="Image"> <ClientSettings> <ClientEvents OnImageLoaded="imageLoaded" /> </ClientSettings> <ThumbnailsAreaSettings ThumbnailWidth="140px" Width="140px" Position="Left" ScrollOrientation="Vertical" /> <Items> <telerik:ImageGalleryItem ImageUrl="images/Image1.png"/> <telerik:ImageGalleryItem ImageUrl="images/Image2.png" /> <telerik:ImageGalleryItem ImageUrl="images/Image3.png" /> <telerik:ImageGalleryItem ImageUrl="images/Image4.png" /> </Items> </telerik:RadImageGallery> <script> function imageLoaded(imageGallery, args) { alert(args.get_image().src); } </script>