Social perception at multiple levels – self-perception, interpersonal perception, and group perception – is central to my work. It is inherently social phenomenon and cannot be studied in isolation from two facts about interpersonal perception: the individual always acts as a perceiver and is always a target of perception. This interplay of self-perception and interpersonal perception is essential to understanding longstanding issues in the field. Are self-perceptions basically accurate or are they characterized by positive illusions? And is accuracy in self-perception or positive illusions elated to mental health? These are some of the questions my work attempts to answer. Cultural perspectives are particularly important in my work because the notion of self differs across individualistic and collectivist cultures. I want to know whether positive illusions of self have the same impact on mental health in collectivist cultures as in Western individualistic cultures. This multi-level approach can also be used to understand the link between the diversity of a group and group performance. Here I focus on self-perception processes and individuation, arguing that self-verification and individuation are necessary conditions for capitalizing on the value of diversity on group performance.