The present study aimed to explain individuals' attitudes toward the dichotomy between uniqueness and universality in human nature as a function of attachment styles. This investigation employed a qualitative approach utilizing a constructivist grounded theory methodology. Participants were purposively selected from among master's students in psychology and counseling based on their scores on the Adult Attachment Inventory (AAI). Sampling continued until theoretical saturation was achieved, ultimately resulting in the participation of 15 individuals (eight with secure attachment styles and seven with insecure attachment styles). Data were collected through in-depth semi-structured interviews and analyzed using a three-stage coding process (open, axial, and selective coding). The data analysis led to the identification of five principal categories: positive experience and valuation of uniqueness and difference; positive perception and emphasis on similarities and commonalities; dialectical attitudes (simultaneity and interweaving of difference and similarity); sources and contexts shaping attitudes toward difference and similarity; and attitudinal transformation over time. The dialectical attitude emerged as the core category, reflecting a simultaneous and complementary understanding of uniqueness and universality within human existence. The findings further indicated that attachment style alone does not play a determinative role in shaping this attitude. Rather than being a passive product of attachment style, attitudes toward fundamental issues of human nature arise from individuals' active agency, overarching worldviews, and the ongoing process of learning and development throughout the lifespan. Nevertheless, the experience of a secure relationship may function as a facilitative context for the perception of commonalities and a tendency toward closeness. The findings of this study underscore the necessity of adopting holistic and multifactorial approaches in the investigation of complex human phenomena.