In 1990, the National Assessment of Educational Progress (NAEP) included a Trial State Assessment (TSA); for the first time in the NAEP's history, voluntary state-by-state assessments were made. The sample was designed to represent the 8th grade public school population in a state or territory. In 1996, 44 states, the District of Columbia, Guam, and the Department of Defense schools, took part in the NAEP state science assessment program. The NAEP 1996 state science assessment was at grade 8 only, although grades 4, 8, and 12 were assessed at the national level as usual. The 1996 state science assessment covered three major fields: earth, physical, and life sciences. In Guam, 930 public schools and 198 nonpublic schools were assessed. This report describes the science proficiency of 6 public school and 8 nonpublic school eighth-graders, compares their overall performance to students in the entire United States (using data from the NAEP national assessment), presents the average proficiency for the three major fields, and summarizes the performance of subpopulations (gender, race/ethnicity, parents' educational level, Title I participation, and free/reduced lunch program eligibility). To provide a context for the assessment data, participating students, their science teachers, and principals completed questionnaires which focused on: instructional content (curriculum coverage, amount of homework); delivery of science instruction (availability of resources, type); use of computers in science instruction; educational background of teachers; and conditions facilitating science learning (e.g., hours of television watched, absenteeism). On the NAEP fields of science scales that range from 0 to 300, Guam students had an average proficiency of 150 compared to 148 throughout the United States. The average science scale score of males did not differ significantly from that of females in either Guam or the nation. At the eighth grade, White students in Guam had an average science scale score that was higher than those of Hispanic and Asian/Pacific Islander students. In Guam, at grade 8, the average scale score of public school students (120) was lower than that of nonpublic school students (147). (DDR/NB)