In this talk, Paul Hewitt, PhD, presents the conceptualization and some of research and clinical work that Hewitt and colleagues have undertaken over the past 30 years in an attempt to gain an understanding of perfectionism, a relational personality vulnerability factor that underlies myriad psychological, physical, relational, and achievement problems. Although often seen as simply a set of attitudes or thoughts, our conceptualization of perfectionism is influenced by a psychodynamic-interpersonal perspective that underscores the relational underpinnings of perfectionism. The talk will focus on describing the multilevel and multidimensional nature of perfectionism, its development, and the clinical formulation and treatment approach we have developed. He will also discuss some of the research they have done on this treatment and, more broadly, on the influence of perfectionism on clinical disorders and treatment.