Introduction: Skin cancer is currently the most common cancer type worldwide, and numbers are rapidly increasing. To improve primary prevention, individualised prevention strategies may be of interest as this enhances the chance of long-term behavioural change. The Sun Exposure and Protection Index (SEPI), previously validated in multiple languages, is a tool that could help identify individuals with risky behaviour and tailor interventions to the person’s propensity to change. The aim of the present study was to investigate the reliability and validity of a Dutch version of the SEPI for both usage in daily clinical practice and research. Methods: Patients were included at primary care settings and dermatology outpatient settings in a 1:1 ratio. Participants were asked to fill out the SEPI together with some baseline characteristics and the previously validated FACE-Q Skin Cancer – Sun Protection module. Construct validity was tested by comparing SEPI part I and the FACE-Q module using Spearman’s Rho. Internal consistency was assessed with Cronbach’s Alpha for both SEPI parts separately. To assess test-retest reliability, the SEPI was again filled out three weeks later, and scores were compared with Cohen’s weighted Kappa. Results: Of the 171 participants completing the first questionnaire, 147 (86.0%) participants also completed the follow-up questionnaire. Comparison between the corresponding SEPI part I and FACE-Q module questions showed good correlations regarding sun exposure habits (correlation coefficients ranging from 0.61 to 0.85). Internal consistency of SEPI part I was 0.63 and SEPI part II was 0.65. The test-retest analysis indicated reproducibility over time (weighted Kappa ranging from 0.38 to 0.76). Conclusion: In conclusion, the Dutch version of the SEPI is shown to be a valid and reliable tool for both usage in daily clinical practice and research to evaluate individual UV exposure and measure a person’s propensity to limit it.