The purpose of the National Girls Collaborative Project is to extend the capacity, impact, and sustainability of existing and evolving girl-serving STEM projects and programs. This paper describes the underpinnings and design of the National Girls Collaborative Project (NGCP) and posits that the structured collaboration framework this organization foments may be a necessary component for our fi eld to move beyond our current levels of representation of women in science, technology, engineering, and mathematics (STEM). Initial results from the projects are described and related to nationwide efforts to increase women in STEM. INTRODUCTION/PROBLEM STATEMENT It is commonly recognized that the representation of women in science, technology, engineering, and mathematics (STEM) fi elds is too low both from a perspective of equal opportunity (Gowan & Waller, 2002; Sadker & Sadker, 1994) and for meeting the projected need of STEM professionals (Chubin, May & Babco, 2005). Studies show that the low representation of women in STEM professions begins as early as eighth grade, when twice as many boys than girls show an interest in STEM careers (Commission on the Advancement of Women and Minorities in Science, Engineering, and Technology Development, 2000), and continues in college, where women received only 21% of bachelor's degrees awarded in engineering, 27% in computer sciences, and 43% in physical sciences (National Science Board, 2006). Factors such as perceptions of careers, confi dence, role models, and career advice have been noted in the literature as contributing to the lack of females in information technology (Bartol & Aspray, 2006). Women constitute 45% of the workforce in the United States but hold 25% of science and engineering jobs and 29% of computer and mathematical occupations (U.S. Census Bureau, 2000). Many organizations and activities are designed with the sole purpose of addressing this problem. However, in spite of this investment, the nation has not experienced signifi cant gains in the representation of women in several key STEM fi elds, e.g., computer science, engineering, and physics. This is particularly true in engineering where, overall, women represent about 20% of undergraduate engineering students; in computer science, women's representation has actually decreased (National Science Board; 2000