Nearly two decades ago, Harkness and Lilienfeld (1997) published a seminal article in which they articulated the potential roles that personality assessment might play in treatment planning. Four broad areas were outlined, including how personality assessment can (a) inform where to focus change efforts, (b) foster realistic expectations of therapeutic gains, (c) facilitate effective treatment matching, and (d) enhance self-development. We review the literature examining the role of personality assessment in treatment, using these four recommendations as a framework. We conclude that more research is needed to test (a) whether changes in characteristic adaptations mediate effects of basic personality dispositions on symptom improvement, (b) the effect of personality on treatment motivation and homework compliance, (c) the role of personality in the prediction of various aspects of psychotherapy, and (d) the efficacy of therapeutic assessment techniques using measures of universal personality traits. We also assert, more generally, that although the field has progressed to some extent in the past two decades, clinical psychologists should cultivate and advance a stronger recognition of how personality assessment can be used to enhance treatment interventions. We believe positive treatment is optimized if psychotherapists or other providers of intervention are equipped with information from personality assessment to select treatment modalities and construct treatment plans.Clinical psychologists possess highly specialized and unique skillsets in their capacity to deliver evidencebased therapies and discipline-specific training in psychological assessment (American Psychological Association, 2016). Yet despite this unique combination of skill and knowledge, it is uncommon for clinical psychologists to use evidence-based personality assessment to inform treatment decisions. One explanation for this is that research examining the role of personality assessment in treatment is not sufficiently developed to inform empirically supported guidelines for psychotherapeutic decision making. There is no shortage, however, of speculation for why and how personality assessments can be used to enhance treatment.Approximately two decades ago, Harkness and Lilienfeld (1997) published a seminal article identifying four ways in which personality assessment can inform treatment planning. These authors suggested that personality assessment could and should be used to (a) inform where to focus change efforts, (b) foster realistic expectations of therapeutic gains, (c) facilitate effective treatment matching, and (d) promote self-development. In the current article, we review the existing empirical research examining the role of personality assessment in treatment, as guided by the framework of these four recommendations. A focus is placed on personality as