The growing number of psychology undergraduate programs and increased quotas for existing programs mean increased competition among psychology students for post-graduation career opportunities. Career adaptability becomes an important factor for a person's employability, career success, and satisfaction under competitive conditions. This study tests a research model formed based on career construction theory with the participation of 355 psychology undergraduates from Istanbul. This model examines participants' demographic variables regarding their family's socioeconomic status, childhood environment, personality traits, and positive psychological capital (PsyCap) as antecedents of career adaptability as well as PsyCap's mediating role in these associations. The results show that, regarding demographic variables, the administrative size of the place where participants spent most of their life positively predicts career adaptability at a low level. Father's education level was found to have a small negative effect on career adaptability. Openness to experience, conscientiousness, extroversion, and agreeableness are the personality traits that positively predict career adaptability, while neuroticism negatively does. PsyCap acts as a mediator between the five personality traits and career adaptability. Among all the variables, the strongest predictor of career adaptability is PsyCap. As such, making investments in developing university students' positive psychological resources using university career centers would be a better strategy for preparing young adults for work life. Future studies are recommended to include demographic variables related to middle and high school education and family -related variables such as parents' personalities, family's career orientations, and values attributed to children in order to better understand the roles demographic and family-related variables have on career construction. In addition to the theoretical model, data pertaining to the participants' career objectives were also analyzed. The analysis results reveal 97.2% of the participants to be planning to apply for a master's degree and 54.6% to have declared pursuing a career in clinical psychology. Considering the scarcity of postgraduate quotas compared to undergraduate quotas, this finding indicates that a significant portion of the participants should be more flexible in managing their post-graduate careers.