6This chapter outlines the psychosocial aspects of mentoring that help women combat the barriers they commonly face in science, technology, engineering, and mathematics (STEM) Effective mentoring, recognized to be an important component in the academic and professional development of women and minorities, may well be one of the most critical elements in the progression of women toward advanced degrees in science, technology, engineering, and mathematics (STEM) fields. In STEM, where, despite progress, the proportion of doctorates awarded to women still hovers around 20% in computer science, physics, and engineering (National Science Board, 2014), and the attrition of enrolled women from doctoral programs exceeds that of men by as much as 9% (Council of Graduate Schools, 2008), the promise of purposive mentoring demands attention.Evidence is accumulating that women' s persistence in the sciences and engineering, a matter of urgent national concern (National Academy of Sciences, National Academy of Engineering, and Institute of Medicine, 2007), is directly linked to the availability of a strong mentor (Preston, 2004). For example, in Preston' s (2004) study, six out of seven women identified a lack of guidance and support as a reason for their decision to leave science. Moreover, women who received mentoring during graduate school completed their graduate programs at a rate of 100%, compared to 60% among women who did not receive mentoring during their graduate years (Preston, 2004). That mentoring is linked to an increase in the probability of completing a program in STEM and that lack of guidance is associated with a greater risk