This proposal describes a workshop, "Advanced Techniques for in situ Studies of Zooplankton abundance, Distribution, and Behavior, "that will be held at Lake Lacawac, NE Pennsylvania, during May 23-25, 1991. The goals of the workshop are: (1) to provide a forum for interaction among biologists who are developing new instruments for studying zooplankton in the field; and (2) to publish a collection of papers that describe instrument development progress to date. This proposal describes the workshop, the people who have been invited, and the relationship of the workshop to other research. Substantial workshop funding has been provided by the Andrew W. Mellon Foundation. We request supplementary funding from NSF to enable key scientists from overseas to attend the workshop and share their knowledge with U.S. and Canadian scientists.