This chapter discusses critical issues, open questions, and future directions in perfectionism research. It addresses three critical issues: focusing on perfectionistic concerns, employing cluster analyses to investigate differences in multidimensional perfectionism, and assessing perfectionism with measures that do not measure perfectionism. Some studies use cluster analyses to examine perfectionism against the theoretical frameworks of two models of perfectionism: the tripartite model of perfectionism differentiating healthy perfectionists, unhealthy perfectionists, and non-perfectionists, and the 2 X 2 model of perfectionism differentiating pure personal standards perfectionism, pure evaluative concerns perfectionism, mixed perfectionism, and non-perfectionism. Studies focusing on perfectionistic concerns represent a regression to the one-dimensional conceptions of perfectionism that dominated the 1980s and risk discounting everything we have learned and achieved in the past 25 years. Any study on perfectionism using more than one measurement point qualifies as a longitudinal study, and any findings from such a study are likely to provide valuable new insights into perfectionism.