In response to the increase in Routine Outcome Monitoring and Clinical Feedback, the Patient-Perceived Helpfulness of Measures Scale (ppHMS) was developed to assess the helpfulness-as perceived by patients-of using measures in psychological treatment. Study 1: The construct of was explored using thematic analysis with 15 patients. Six helpful and three unhelpful themes were identified and informed item development. Study 2: 28 items were formulated and rated by experts. Ten items were taken forward for psychometric shortening in a sample of 76 patients. Confirmatory factor analysis (CFA) led to an adequately fitting six-item model with excellent internal consistency, and convergence with the Delighted-Terrible single item of product satisfaction and a single item of measure helpfulness. Study 3: In a stratified online sample of 514 U.K. psychotherapy patients, a five-item model constituted the best fit. The final ppHMS had excellent internal consistency (McDonald's ω = .90), convergent validity with psychotherapy satisfaction ( = .5; < .001), divergence from social desirability ( = .1), and metric and scalar invariance across measures. Study 4: Analyses were replicated and confirmed in a stratified U.S. sample ( = 602). The ppHMS is a reliable and valid scale that can be used to assess and compare patients' perceptions of the helpfulness of different measures as part of their psychological treatment.