Brazil is experiencing an accelerated period of population aging, with important implications for individuals, families, and the society at large. Lifestyles for the elderly can have both positive and negative health effects and are characterized by behaviors that individuals constantly reproduce in day-to-day life. However, few assessment instruments are aimed at evaluating lifestyles, and this has hampered research development. Thus, our aim in this study was to develop and evaluate the psychometric qualities of a new instrument to assess older adults’ lifestyles. We developed this single scale to assess the lifestyles of older men and women using the sequential mixed method. Individuals over 60 years old of both sexes participated in this study of several phases. In Phase 1, we produced a 96-item single scale instrument, based on a literature review, previous scales, and qualitative research. In Phase 2, we verified the scale’s content validity with help from 12 experts and 20 members of a target audience, aged between 60-84 years, deleting some items and reworking others. In Phase 3, we analyzed the psychometric qualities of the new scale in a sample of 700 older adults, aged 60 and above, from the five regions of Brazil, using both exploratory and confirmatory factor analysis. Our completed “Older Adult Lifestyle Scale” (OALS) is composed of 19 items divided into four subscales. The OALS has shown good psychometric qualities for Brazilian older adults over 60 years of age, and we can now recommend its use in this population.