Objective: To linguistically and culturally adapt the Perceived Stress Questionnaire (PSQ) by Levenstein to the Ecuadorian context and to validate its psychometric properties in an adult population. Method: The process followed five phases: translation and back-translation, expert review, two pilot tests (N = 600), exploratory factor analysis (395 participants), confirmatory factor analysis (391 participants), and sex-based invariance analysis. A non-clinical sample was selected to ensure that results represent the normative range of perceived stress in the general population. Reliability was assessed using Cronbach's alpha and McDonald's omega, while convergent and discriminant validity were examined through correlation analyses. Results: The general version was optimized to 23 items across three factors, explaining 49.8% of the variance, while the specific version comprised 21 items in four factors with a distinct structure, accounting for 54.97% of the variance. Both versions demonstrated excellent internal consistency (α y ω > 0,90) and satisfactory fit indices in the CFA (χ²/gl ≈ 2,2; CFI ≈ 0,92; RMSEA ≈ 0,056). Construct validity was confirmed, and metric and scalar invariance by sex supported their use in group comparisons. Conclusions: The Ecuadorian adaptation of the PSQ is a valid and reliable instrument for assessing perceived stress in adults. The specific version is suitable for detecting acute stress and monitoring short-term interventions, while the general version is appropriate for longitudinal studies. These findings reinforce evidence of cross-cultural validity and provide a foundation for developing national norms and mental health promotion programs.