Investigating the concepts affecting individuals' attachment styles in early adulthood is essential for healthy and satisfying social and emotional/romantic relationships. The purpose of this study was to examine the direct effects of self-esteem, loneliness, and emotional dependency on university students’ attachment styles. In addition, this study investigated the mediating roles of emotional dependency and loneliness on the relationships between attachment styles and self-esteem. The research group consisted of 518 volunteer university students in their first adulthood. Demographic Information Form, Rosenberg Self- Esteem Scale (RSES), Experiences in Close Relationships- Revised (ECR- R), Emotional Dependency, and UCLA Loneliness Scale were used to collect the data. Pearson moments correlation coefficients, hierarchical regression analyses, and bootstrapping methods were performed to test the hypotheses. The results of hierarchical regression analysis showed that self-esteem negatively and loneliness positively predicted anxious and avoidant attachment styles. Emotional dependency positively predicted anxious attachment and negatively predicted avoidant attachment styles. In addition, the bootstrapping analysis showed that loneliness played a significant partial mediator role on the relationships between self-esteem and avoidant and anxious attachment, while emotional dependency was not a significant mediator. The findings were discussed along with the theoretical basis and the previous findings, and suggestions were presented for future studies.