This handbook represents an attempt by UNESCO to give a broad picture of the kinds of out-of-school activities that are designed to engage the participation of young people in different parts of the world. Out-of-school activities, as used in this publication, refers to educational activities undertaken or done outside the formal teaching periods and the formal curriculum. Activities discussed are grouped under the following chapter headings: Clubs, Science Fairs, Camps, Meetings, Museums, Nature Conservation, Non-Specialized Agencies, and Administration. The format of each chapter is similar in that the particular out-of-school science activity under discussion is first described in general terms and then illustrated by programs that are operational in several countries. (BR)