After the very successful Third ROOT Users Workshop in June 2001 at Fermilab we are happy to annouce the Fourth ROOT Users Workshop, to be held at CERN the 14th, 15th and 16th of October 2002. As the use of ROOT continues to grow at a rapid pace it remains important to continue meeting at a regular basis to discuss technical issues, share ideas and plan directions for future development. To register and submit abstracts go to the registration page. For any inquiries or comments contact directly the organizers. The registration fee is CHF 20,-, which includes the workshop dinner, coffee breaks and a printed copy the Users Guide. If you cannot attend, but would like to make a presentation, we will have a VRVS setup in operation (No camera, only voice). Here are the Virtual Planets where to connect(No password required): Monday 14th October from 09:00 AM to 05:00 PM: NEPTUNE Tuesday 15th October from 09:00 AM to 05:00 PM: NEPTUNE Wednesday 16th October from 09:00 AM to 06:00 PM: VENUS We are particularly interested by talks in the following categories: use of Root as a general framework. experience with I/O, comparing different solutions using Trees or other mechanisms. use of the Root/CINT dictionary to implement interfaces with foreign systems. Use of the GUI and graphics classes. use in DAQ, Real time systems and client/servers. distributed applications on the GRID. Statistical Analysis tools and classes. We also invite participants to come with questions, comments, proposals to be discussed in a special Q&A session.