The question, "What constitutes a reasonable, useful agenda for research into science learning in out-of-school, free-choice environments?" has surfaced with increasing frequency over the past 10 years or so. One event that helped move the agenda forward was the National Science Foundation-funded conference, "Public Institutions for Personal Learning: Understanding the Long-term Impact of Museums," held in Annapolis in 1994. The proceedings of this conference, published by the American Association of Museums (Falk & Dierking, 1995), reflected a large step forward in setting out the research issues and questions involved. Although focused on museums (a generic term including all kinds of museums, botanical gardens, aquaria, zoos, and science and other interpretative centers), the issues discussed are applicable to a wide range of non-museum contexts. The Annapolis conference was conceived as a forum for frontline researchers in a variety of fields representing the physical, social, and personal dimensions of learning. The goal was to discuss how the thinking and modalities of their disciplines might shed insights into the nature of learning and be used to define and lay out a long-term research agenda in museums. At about the same time, a small group of science museum practitioners held several meetings under the auspices of the Association of Science and Technology Centers (ASTC) and the Institute of Museum Studies (IMS) to start thinking about a research agenda in their area of expertise. The results of the think tank meetings were published in six successive ASTC newsletters during 1996 (and are now available at http://www.astc.org/resource/educator/educmain.htm#theories).