The Environmental Health Sciences Center for Developmental and Molecular Toxicology at the University of Wisconsin-Madison (EHS Center) is conducting a symposium series in developmental toxicology, the first of which was held in June 1999. The proposed meeting, the second of the series, will take place June 1-2, 2000 at the University of Wisconsin's Pyle Center. This campus location is a well-equipped conference facility suitable for the proposed numbers of attendees. Participants will include speakers from both within and external to the university, well- known experts in their respective fields of research. The audience will consist of local and national researchers, industry representatives, graduate students and postdoctoral fellows. The Center's goal in presenting these meetings is to bring together researchers in toxicology and particularly developmental toxicology with experts in developmental biology, biotechnology, and other relevant, basic-science disciplines. We wish to foster collaboration between these groups because we recognize that developmental aberrations may result from several processes, including interference with cell function, genotoxicity, and inappropriate cell-cell signaling. The series of three meetings examines different aspects of developmental toxicology in relation to our understanding of the underlying mechanisms. The first meeting examined the extent of the environmental and pharmaceutical contribution to developmental deficits, appropriate model systems, and emerging pathways regulating morphogenesis and neurogenesis. The second meeting addresses mechanisms by which the activation of the Ah receptor (AhR) by dioxin, PCBs and other environmental activators leads to developmental disruption and deficits. There will be an emphasis on effects in the embryo and on endocrine disruption of early development. The meeting will focus on signaling mechanisms involving AhR, including the use of genetic models for development. There will also be an emphasis on the use of new technologies to address these problems. The meeting will begin on Thursday afternoon, June 1, and continue through Friday, June 2, lasting one and one-half days. The afternoon of the first day will include a public forum organized by the EHS Center COEP to address local issues of concern relating to PCBs. Posters presented by graduate students and postdoctoral trainees will also be on display for discussion with the public and scientists alike. The evening of the first day will feature a plenary lecture followed by a social hour. The second day of the symposium will consist of two, 4-hour sessions. Each session will conclude with a discussion period for assessment of key goals for future research. Summaries of the proceedings will be generated for non-specialist audiences and for the general public. A summary of the proceedings will be submitted for publication to Environmental Health Perspectives.