The main aim of the present study was to test the psychometric properties of the Sexual Desire and Erotic Fantasies questionnaire -Part 1 Sexual Desire (SDEF1), developed as a sex-positive measure of different sexual desire expressions. The SDEF1 was assessed with 1,773 Italian participants (1,105 women, 645 men, and 23 other genders). The final version showed a 6-factor structure including 28 items: sexual desire, negative feelings to sexual desire, autoerotic desire, regular partner desire, attractive person desire, and responsive desire. The SDEF1 revealed good psychometric properties such as internal reliability, construct, and discriminant validity, and has shown to be able to differentiate women and men with and without sexual dysfunctions/problems. Results of the current study seem to validate the idea that the SDEF1 could be a useful measure to assess different areas of sexual desire and its use could be recommended for clinical and research purposes.