There isn't a physical limit in Designer, however each form takes resources to operate. The more functionality you build into a form, in particular a large form, the more resources it will take to drive it. At some point Acrobat/Reader will fall over and crash. For example some events are efficient, but others, if used unwisely, are very inefficient. Have a look at the layout:ready event: http://assure.ly/nB0Bvz. Niall