The adaptation of a test from a language into that same language in another culture is common; however, there are no clear guidelines for this process. The objective was to adapt a protocol providing some guidelines for adapting questionnaires from one language to the same language. A total of eight experts supported the adaption process and 825 participants from Spain and Colombia were evaluated in this study. Participants answered the brief version of the Sexual Assertiveness Scale, the Sexual Opinion Survey, the Massachusetts General Hospital-Sexual Functioning Questionnaire and the Sexuality Scale. The adaptation was made following some guidelines which have already been published. The results showed a strong partial invariance between countries. DIF analysis also replied this partial invariant form and adequate psychometric properties; guidelines to adapt questionnaires into same language in other cultures are presented. Therefore, the adaptation process - in the absence of further evidence - could be effective.
