This paper describes the development, administration, and results of an instrument to assess changes in students' science abilities as they progress from ninth grade through twelfth grade. Standard science tests commonly in use in schools to measure high school science students' achievement are content specific. Although these tests are useful they do not tell teachers or other educators what skills or general science knowledge students have acquired, nor can they ascertain students' progress as they move through high school. As part of the evaluation of the WINNERS II Project described in this paper, the research team wished to know more about what students were taking away from their science classes as they made their way through four years of high school. The research team decided to focus on designing a test that measured (1) understanding of the nature of science; (2) use of skills to solve problems; and (3) development of skills to use science equipment. (Contains 13 references and 3 tables.) (Author/WRM)