AbstractBertalanffy's general system theory (GST) was conceived as a unifying research program, as a science of ‘wholeness’ to overcome or complement mechanistic and reductionist approaches. More than 50 years since the founding of the Society for General Systems Research (SGSR), today's International Society for the Systems Sciences (ISSS), two questions arise about the developments in GST research. Are there recent contributions towards enhancing GST? Are there simplifications compared to Bertalanffy's original program? To answer these questions we analysed in detail 161 articles in peer reviewed journals that referred to GST and appeared between 1995 and 2006. We emphasized contributions made in science and philosophy. Even though the system approach was introduced in applied fields such as engineering and management, we did not include these fields in this article. Copyright © 2010 John Wiley & Sons, Ltd.