Techniques for establishing a screen sharing session are described. Consistent with some embodiments, a web conferencing application executing at a mobile computing device enables a user to specify the identity of a remote computer. The identity of the remote computer is communicated to a web conferencing service, directing the server operating the web conferencing service to establish a remote desktop connection with the remote computer. Once established, the web conferencing service receives from the remote computer a stream of information representing a user interface of the remote computer, and then broadcasts the user interface to all computing devices participating in the web conferencing session, while enabling the mobile computing device to manipulate the user interface of the remote computer.