Mathematics competency continues to limit the success of many students and prevents their completion of a postsecondary degree, which ultimately prevents access to education, jobs, and upward social mobility. Furthermore, many postsecondary institutions admit students who do not meet the institution's mathematics proficiency requirements and then require these students to take developmental mathematics courses. In order to gain a better understanding of developmental mathematics students and to develop programs and interventions to facilitate increased student success, it is vital for researchers to examine the effects of motivation and learning strategies. The purpose of this research was to identify if there is a statistically significant relationship between students' motivation, mathematics anxiety, perceived learning strategy use, group demographic characteristics, and mathematics competency. In order to establish the nature of this relationship, a quantitative research study was conducted at an urban, postsecondary institution with students enrolled in developmental mathematics. ANOVA, t-tests, MANOVA, chi-square, and multiple regression analysis were used to determine if statistically significant relationships exist. The link between self-efficacy and students' mathematics competency was emphasized throughout this research study. Multiple regression analysis found that regardless of other variables or demographic characteristics, self-efficacy continued to be a significant factor with significant predictive utility. As additional variables were entered into the regression model, including perceived use of learning strategies and mathematics anxiety, the predictive utility of the model did not increase. Furthermore, analysis revealed that certain demographic characteristics, age and race/ethnicity; also have a significant effect on mathematics competency. Non-traditional age students were found to do significantly better in developmental mathematics courses and report higher task-value, intrinsic motivation, use of elaboration skills, and time and study environment skills than traditional age students. African American students were found to have significantly lower mathematics competency than White and Latino students. Finally, additional ANOVA analysis concluded that self-efficacy, elaboration, intrinsic motivation, extrinsic motivation, and mathematics anxiety all had a significant effect on students' success in the developmental mathematics course. Ultimately, the results presented in this research study are significant and should be used to increase student success in developmental mathematics courses. The findings in this research study extend previous findings from other research on motivation, learning strategies, and mathematics competency in postsecondary developmental mathematics courses. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]