Background: The Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) is a pan-theoretical and pan-diagnostic measure of mental health designed to cover issues that people wish to change in psychotherapy. The objective of this study was to explore the psychometric properties of the Spanish translation of the CORE-OM, in a country, Ecuador for which there is not a single measure suitable for this purpose with empirically demonstrated local acceptability and psychometric properties. Methods: In total, 886 adults not currently receiving psychotherapy treatment or taking psychotropic medication were included in the analysis. The analyses broadly followed and compared with results from previous studies. These analyses consisted of assessment of acceptability, internal consistency, test-retest reliability, influences of demographic variables, correlations between domain scores, and convergent validity with Spanish versions of the Outcome Questionnaire 45.2 and Schwartz Outcome Scale-10. Results: The questionnaire showed good acceptability (overall omission rate of 0.56%), good reliability (α = .93 [.92, .94], test-retest correlations ranged from .59 to .85), and good convergent validity with the Outcome Questionnaire 45.2 (r = .84) and the Schwartz Outcome Scale-10 (r = −.73). Statistically significant gender differences were found in two domains: females scored higher on Well-being (M = 1.23) than males (M = 1.01), though effect size was small (g = 0.31); and males (M = 0.31) scored higher than females on Risk (M = 0.25), with even smaller effect size (g = 0.06). Age was negatively correlated with psychological distress in all domains and coefficients ranged from −.14 for Risk to −.29 for Functioning. Conclusions: The results support the use of the CORE-OM as a valid and reliable instrument in a non-clinical Ecuadorean population. Exploration of the psychometric properties in a clinical population is recommended to assure its use in clinical settings.