This chapter outlines a range of methods for developing a comprehensive schema therapy assessment, including clinical interview, identification of key problem areas and related therapy goals, functional assessment of key problem areas, self-monitoring forms, mode assessment, questionnaires and psychometric data, diagnostic imagery, and process assessment. The assessment process largely continues throughout the entire therapeutic process, as more information is understood and revealed, allowing for reformulation and fine tuning. Throughout the assessment process the schema therapist suggests possible links between current presenting issues and interpersonal patterns, early attachment processes and schema development. This process is aimed at building rapport through deep attunement and transparency, whilst providing education about schema development, thereby gradually strengthening the client’s capacity to self-reflect. A shared formulation (even if tentative) provides the groundwork for the therapeutic process. It is therefore essential to spend sufficient time exploring childhood and adolescent issues and the way in which these link to presenting issues.