The report describes the implementation and continuing documentation of a Japanese second language program in a laboratory elementary school at the University of Pittsburgh (Pennsylvania). The structure of the curriculum and instructional strategies used are described for each of the program's 2 years, and results of student assessments and surveys of students, parents, and teachers are discussed. Adjustments made in the program's second year in response to issues arising in the first year are also noted. Documentation instruments, data collection procedures, and results are also detailed, including vocabulary testing, oral interviews, learner questionnaires, teacher assessments of students' language development, parent questionnaires, and reflections of the Japanese teacher and other primary teachers in the school on the effects of the program. From these results, implications are drawn for policy formation, the role of the program in the school's culture, curriculum and materials development, articulation, and the utility of current Japanese proficiency measures. (MSE)