The Children's Museum of San Jose, in collaboration with developmental psychology researchers at UC Santa Cruz (UCSC) and science and education staff of the UC Berkeley Museum of Paleontology (UCMP), is conducting a 48-month long project that focuses on children's use of evidence to construct scientific explanations. Key deliverables are: a 2,300 square-foot paleontology exhibit with an Evidence Central area three "evidence hubs" at the Children's Museum of San Jose, an educational Web site developed by UCMP, research on children's use of evidence conducted by Maureen Callanan's research group at UCSC, a "state of the children's museum field" study on varieties of perspectives on "science" and "evidence," and professional development experiences for staff at children's museums. Additional partners include the children's museums in Austin, TX, Madison, WI, and Providence, RI and local Vietnamese and Latino organizations in the museum's neighborhood. Randi Korn & Associates will conduct the program summative evaluation process and the "state of the field" study. The project identifies and will work to address two specific needs in the field: (a) a clearer sense of the developmental progression of children's understanding of evidence, and (b) a rigorous and systematic investigation of children's open-ended reasoning about evidence in a rich content domain (paleontology). The strategic impact goal is to build capacity in children's museums, enabling them to offer more evidence-based science learning experiences for their visitors.