Outcome measures are important assessment tools to evaluate clinical genetics services. Research suggests that perceived personal control (PPC) is an outcome valued by clinical genetics patients and clinicians. The PPC scale was developed in Hebrew to capture three dimensions of PPC: Cognitive, decisional, and behavioral control. This article reports on the first psychometric validation of the English translation of the PPC scale. Previous research has shown that the Hebrew and Dutch translations have good psychometric properties. However, the psychometric properties of the English translation have not been tested, and there is disagreement about the factor structure, with implications for how to score the measure. A total of 395 patients attending a clinical genetics appointment in the United Kingdom completed several measures at baseline, and a further 241 also completed measures at 2–4 weeks follow-up. The English language PPC has (a) a one-factor structure, (b) convergent validity with internal health locus of control (IHLC), satisfaction with life (SWL), depression, and authenticity, (c) high internal consistency (α = 0.83), and (d) sensitivity to change, being able to identify moderate changes in PPC following clinic attendance (Cohen's d = 0.40). These properties suggest the English language PPC measure is a useful tool for both clinical genetics research and for use as a Patient Reported Outcome Measure (PROM) in service evaluation. © 2011 Wiley Periodicals, Inc.