This study investigates the development of prospective teachers' observation skills and understanding of assessment in two teacher education programs that integrate information about performance assessment in varying degrees into their preparation and field experiences. Focusing on eight student teachers, we used interview data to investigate the influence of exposure to principles of a curriculum-embedded performance assessment--the Work Sampling System[TM]--through use of a handbook for teacher educators and student teaching placements. We found that when the preparation experiences were supported by placements in which assessment was ongoing and curriculum-embedded, student teachers demonstrated strengths in their assessment skills and understanding. Implications for future research and teacher preparation programs are discussed. (Contains 2 tables and 1 footnote.)