This study used a five-step procedure to establish and validate the essential competencies in computer literacy for elementary and secondary school (grades K-12) science teachers. This procedure produced a concise list of 24 competencies that are not only representative of the broad field of computer literacy skills, but also are considered to be essential for science teachers. These competencies fall into the categories of: computer awareness; applications of microcomputers in science education; implementing microcomputers in science teaching; selection and evaluation of software; and resources for educational computing. (Computer programming, the history of computing, and computers and society were not rated as essential competencies.) The 24 competencies will be used to develop: (1) a test for measuring the computer literacy of science teachers; and (2) a curriculum for training science teachers to use the computer. The test and the curriculum will be used by both preservice and inservice science teachers to successfully implement educational computing. Tables showing factors for essential computer literacy competencies and providing descriptive statistics for 24 essential and 21 secondary competencies are included. (Author/JN)