The International Workshop on human lactation dedicated specifically to the topic of Maternal and Environmental Effects on Lactation repre sents the recent progress of research in human lactation. Only four years ago it was clear that we do not yet have sensitive research techniques specifically adapted to the study of human milk. This need was addressed by an NIH convened workshop in 1982, the concensus being that appropriate methods have to be developed for the study of the composition of human milk. The progress in the development of these techniques was the subject of the second workshop on human lactation, dedicated specifically to "Milk Components and Methodologies. " The workshop was held in Colorado in 1984 and resulted in the publication of the first volume in the series of "Human Lactation. " At the Colorado meeting it was readily apparent that considerable progress has been made in the development of sensitive techniques able to quantitate the bioactive components of human milk (enzymes, growth factors, immuno-protective agents) as well as the macro, micro and trace elements. At the Colorado workshop it became clear that these workshops greatly benefit the research of human lactation by enhancing communication and collaboration among the investigators in the field. As a result it was decided to have a future workshop about a year later on the topic of "Maternal-Environmental Effects on Human Lacta tion," and I was charged with chairing it."