Objective: The aim of this study was to assess the factor structure of the English version of the Young Schema Questionnaire Long Form-3 (YSQ-L3) using a large clinical sample and smaller non-clinical population. The items in the YSQ-L3 were evaluated as to how well they assess the underlying theoretical constructs of schema and schema domains. Method: A primary and a higher order factor (HOF) analysis was undertaken on a large heterogeneous clinical sample (N = 574) and the total sample (N = 838) that included a small non-clinical population (N = 264). Results: The primary factor analysis revealed 20 early maladaptive schemas (EMS). Of the 232 items, 182 loaded above.4 and were retained for the final analysis. The original Emotional Inhibition schema separated into Emotional Constriction and Fear of Losing Control, and Punitiveness likewise separated into Punitiveness (Self) and Punitiveness (Other). The HOF analysis indicated four domains: Emotional Dysregulation, Disconnection, Impaired Autonomy/Underdeveloped Self, and Excessive Responsibility/Overcontrol. These overlap with the domains proposed by Young et al. (2003) but with some differences. The Emotion Dysregulation domain was unique to the current study. The mean item loading for each factor ranged from.52 to.82. The revised scale showed excellent overall internal consistency (a =.91). Conclusion: This is the first study that investigated the psychometric properties of the English version of the YSQ-L3. The resultant domains fitted with existing literature of meaningful clinical phenomenon such as attachment and emotion dysregulation and their role in maintaining chronic psychological disorders.