Achievement for girls and boys in STEM subjects is equal at all levels of school, but shocking inequalities persist in participation, especially as levels get higher (Boaler & Sengupta-Irving, 2006). This restricts girls’ access to a wide range of jobs; it also impoverishes the disciplines of mathematics, science and engineering enabling a cycle of inequality to continue. Many factors contribute to the decisions girls make, some of which have received extensive funding and attention. The need for role models, and the positive contribution played by after school clubs and camps that engage girls in STEM work are well understood and documented (GSUSA, 2008). But important and actionable causes of inequality have been neglected in recent decades and new research evidence underscores their importance. These may be considered under two broad headings: (1) Teaching and Identity development and (2) Beliefs and Messages.