Project Learning Tree (PLT) is a supplementary environmental education program intended for use in and out of the classroom with young people, their leaders, and teachers in kindergarten through grade 12. The PLT curriculum provides supplementary activities in various subject areas, such as social studies, language arts, mathematics, science, and art. This document provides both a description and rationale for the program. It also details the process through which the program has evolved since 1976. It includes sections dealing with: (1) the goals of PLT; (2) how the PLT process works; (3) the administration of PLT; (4) some of the distinguishing features of PLT; and (5) examples of some of the national recognition the program has received. Attached is a brief flyer that summarizes and promotes the program, along with three issues of "The Branch," PLT's newsletter. (TW)