This paper describes an intergenerational science program called Sisters in Science which fosters girls' interest and achievement in science. The program is designed to encourage and prepare girls and women for careers in math, science, and technology. A group of fourth grade girls from 19 classrooms across 6 elementary schools met once a week after school. The girls participate in gender-sensitive, constructivist, integrated mathematics and science instruction; 2 hours of instruction from preservice teachers from Temple University; and a 2-week summer camp experience. Findings suggest that the girls in the program increased their interest and achievement in science and mathematics. Data supports a positive pattern of change in the girls' science/math and language skills as evidenced by their class participation and the writing in their science journals. In addition, three policy and practical implications are cited from the study. First, programs must involve parents in the effort to foster the success of young females in science and mathematics. Second, involving intergenerational role models in school science and mathematics enhances female achievement in science and mathematics. And finally, program interventions evolve in stages of development, growth, and change. (Contains 52 references.) (CCM)