The Complex Adaptive Systems as a Model for Network Evaluations (CASNET) study was a four-year research project investigating evaluation capacity building (ECB) within a network using a complexity theory lens. The study used a case study approach to examine and understand evaluation capacity building within the Nanoscale Informal Science Education Network (NISE Net). NISE Net is a national community of researchers and informal science educators dedicated to fostering public awareness, engagement, and understanding of nanoscale science, engineering, and technology. Instituted in 2005 through NSF funding (DRL-0532536 and 0940143), NISE Net has continuously expanded and is currently comprised of close to 600 science museum and university partners. The intent of the CASNET project was to provide insights on (1) the implications of complexity theory for promoting widespread and systemic use of evaluation within a network, and (2) complex system conditions that foster or impede ECB within a network, i.e., in this case, within the NISE Net.