"After-School Math PLUS (ASM+)" uses the rapidly growing field of informal education as a venue to develop positive attitudes, build conceptual knowledge, and sharpen skills in mathematics for underserved youth in grades 3-8. "ASM+" brings families and children together in the pursuit of mathematics education and future career interests and directly addresses the NSF-ISE's four areas of special interests: (1) builds capacity with and among informal science education institutions; (2) encourages collaborations within communities; (3) increases the participation of underrepresented groups; and (4) models an effective after-school program. " ASM+" is being developed in collaboration with the New York Hall of Science and the St. Louis Science Center with support from after-school centers in their communities. "ASM+" incorporates the best practices of existing programs, while adding its own innovative elements that have proven successful in the NSF-funded "After-School Science Plus" (HRD #9632241). "ASM+" is aimed at underserved youth and their families, as well as after-school group leaders and teenage museum explainers who will benefit from training and participation in the project. It has facilitated the creation of alliances between museums, after-school centers, schools and the community