Hi, I just committed a change to R-devel so that if debug is called on an S3 generic function, all methods will also automatically have debug turned on for them (if they are dispatched to from the generic). I hope to be able to extend this to S4 and a few other cases that are currently not being handled over the the next few weeks. Please let me know if you have problems, or suggested improvements. Robert -- Robert Gentleman, PhD Program in Computational Biology Division of Public Health Sciences Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N, M1-B514 PO Box 19024 Seattle, Washington 98109-1024 206-667-7700 rgentlem at fhcrc.org