private void MixedForm_Load(object sender, EventArgs e) { WPFWindowLibrary.UserControl1 control = new WPFWindowLibrary.UserControl1(); // Create the ElementHost wrapper. ElementHost host = new ElementHost(); host.Child = control; // Set the Location and Size explicitly, unless you are using // a layout container like FlowLayoutPanel or TableLayoutPanel, // or you are using docking. //host.Location = new Point(10, 10); host.Size = new Size(flowLayoutPanel1.Width, flowLayoutPanel1.Height); // Add the ElementHost to the form or another suitable container. flowLayoutPanel1.Controls.Add(host); }