From Diversifying Economic Quality: A Wiki for Instructors and Departments
Foster a growth mindset in your students.
Students can be stuck in the mindset that intelligence is inborn and thus cannot be expanded. Students who identify with groups underrepresented in a particular academic field, such as economics, may get a message that they are less capable of contributing to that field.
How to foster a growth mindset
It is important to tell students that:
Intelligence is malleable. Burgeoning evidence in cognitive psychology and neuroscience demonstrates the malleability of intelligence and the plasticity of the brain. See, for instance, Jaeggi, et al. (2008).
Math ability can be developed. Don't accept a student's statement that she is not a "math person."
Economic intuition can be acquired. Why else do we teach?
Race and gender are social constructions. Watch The myth of race, debunked in 3 minutes
Academic skills and abilities are acquired through hard work, mistakes, and perseverance.
Evidence of positive effects
Researchers have produced (and replicated) significant evidence on the effects of growth mindsets on academic achievement, including in math and science courses.   As Carol Dweck writes, "Students who believe that intelligence or math and science ability is simply a fixed trait (a fixed mindset) are at a significant disadvantage compared to students who believe that their abilities can be developed (a growth mindset). Moreover, research is showing that these mindsets play an important role in the relative underachievement of women and minorities in math and science...[and that] educators play a key role in shaping students’ mindsets." 
Yeager, Walton, and Dweck tested full-scale implementation of a web-based growth mindset intervention in a randomized experiment conducted at a large four-year university in Texas.
A landmark study by Aronson, Fried, & Good (2002) found that "encouraging students to see intelligence as malleable (i.e., embrace an incremental theory of intelligence) can raise enjoyment and performance in academic contexts." In their experiment, college students in the treatment group learned an incremental theory of intelligence and wrote a letter explaining the theory to a low-performing middle school pen pal. "The African American students (and, to some degree, the White students) encouraged to view intelligence as malleable reported greater enjoyment of the academic process, greater academic engagement, and obtained higher grade point averages than their counterparts in two control groups."
Research has also shown that "when teachers believe in fixed intelligence, the students they identify as having high ability are the only ones who tend to achieve well in their classes. When teachers hold a growth mindset, a much broader range of students do well." (Rheinberg, 2000, as cited in Dweck, 2008)
Recently, economists Miles Kimball and Noah Smith tapped into this same body of research on the malleability of math ability and concluded that "there's one key difference between kids who excel at math and those who don’t" on Quartz.
Dweck, C. (2008). Mindsets and math/science achievement. New York: Carnegie Corporation of New York, Institute for Advanced Study, Commission on Mathematics and Science Education as cited in Hill et al. (2010). "Why so Few? Women in Science, Technology, Engineering, and Mathematics". American Association of University Women.
Jaeggi, S.M., Buschkuehl, M., Jonides, J., & Perrig, W.J., Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences, 2008.
Rheinberg, F., Vollmeyer, R., & Rollett, W. (2000). Motivation and action in self- regulated learning. In M. Boekaerts, P. Pintrich & M. Zeidner (Eds.), Handbook of self-regulation (pp. 503-529). San Diego: Academic Press.