<p>Sexuality has been robustly linked to older adults’ well-being. Although several approaches to measuring sexual health and sexual well-being in this population have been recently proposed, their conceptual framework is unclear or missing. Following the gerontological successful aging paradigm that focuses on dynamic adaptive processes, we constructed and tested a new measure intended to assess positive sexual aging. Using two probability-based samples of partnered women and men aged 65+ years (<i>n</i> = 727) from Norway and Croatia, we tested dimensionality, measurement invariance, associations with other relevant constructs, and network-of-items topology of a brief 4-item measure. This new measure—the Brief Positive Sexual Aging Scale (BIPSAS)—was invariant across country and age, but not gender. Marked gender differences were also found in the measure’s network-of-items topology. Scores on the measure were significantly and meaningfully related to indicators of sexual communication and activity, relationship and life satisfaction, and psychological health. The opportunities for sexual expression facet had the highest overall centrality in the BIPSAS network, echoing its heightened importance for older people’s sexuality. With a caveat that positive sexual aging in older women and men may not be directly comparable, this psychometrically sound and brief measure is suitable for use in a wide range of studies focusing on health, well-being, and sexuality among older partnered adults.</p>