this book constitutes the thoroughly refereed post-proceedings of the 4th international workshop on learning software organizations, lso 2002, held in chicago, il, usa, in august 2002, in conjunction with xp/agile universe 2002. the book is devoted to technical, organizational, and social solutions to problems of learning from past experiences and codifying the resulting best practices so they can be systematically used in subsequent software development efforts. the nine revised full papers presented with an introductory overview were carefully reviewed and selected for presentation. they are organized in topical sections on agile learning, distributed learning, process-centered approaches, and models for organizational learning.