This is a topic generally covered in the IDL Online Help subtopic "Calling PDF Files". You can find this article from the Online Help Contents tab page in the following documentation path: 'IDL Programmers' Guides > Application Programming > Part III: Creating Applications in IDL > Providing Online Help For Your Application > Using Other Online Help Viewers'. It will show you how to use IDL's ONLINE_HELP procedure to get your personal PDF files to load in your system's default PDF Viewer. I think that several years ago, ONLINE_HELP could open up PDF's in IDL's own Help viewer, but that possibility ended when IDL switched to using 'HTML Help' software several years ago. So now ONLINE_HELP typically opens up the PDF files in Acrobat Reader. James Jones