The purpose of this action research study was to explore the relationship between growth mindset instruction in a community college success class with student academic effort and achievement, among students enrolled in a developmental reading class. Community college students, especially those testing into developmental classes, face numerous obstacles to achieving their goal of completing a college degree. Research supports that students with a growth mindset - a psychological concept grounded in the belief of the malleability of traits such as intelligence - embrace challenges, exert more academic effort, and achieve more. Fourteen students enrolled in a community college participated in this convergent parallel mixed methods study. A mindset survey was administered three times, at the beginning and end of the semester as well as at Week 3 after initial introduction to growth mindset. Descriptive statistics indicated a slight increase in students’ growth mindset scores by the end of the term. An analysis of variance, however, yielded no statistically significant relationship. Correlational analysis of final mindset scores with effort variables indicated an unexpected result – a negative correlation (p<.05) of growth mindset with time in Canvas (the Learning Management System). An ANOVA using a median split for high vs. low mindset scores indicated an unexpectedly significant (p<.05) positive relationship between missing assignments and a high mindset score. Statistical analysis of mindset with achievement yielded no significant relationship. Qualitative results included data from three journal assignments and semi-structured interviews and suggest that these students could comprehend and support most of the tenets of Growth Mindset Theory. While quantitative results were not significant in the expected direction, triangulation with qualitative data indicated that students’ goal orientation may be a factor in the unexpected quantitative results. This study adds to the growing literature on Growth Mindset Theory by extending it to a new and different population, first year community college students, with reading challenges. Further study is needed to clarify the relationships of growth mindset, malleability of intelligence, and goal orientation with academic effort and achievement over a longer period.