At around age 60, people are approaching late adulthood and are typically going through or anticipating life transitions such as grandparenthood, retirement, or changes in health and functioning. The timing and perception of transitions are individual and based on current circumstances and earlier life history and may link to well-being. The TRAILS (Developmental Psychological Perspectives on Transitions at Age 60: Individuals Navigating Across the Lifespan) study, which is presented in the current article, examines the diversity and underlying factors of different transitions at around age 60 and how they associate with mental well-being. It also investigates whether these transitions link to personality characteristics, contextual resources, and/or societal challenges. The role of earlier life history in the studied associations requires a prospective multiwave design where the same participants are followed over time. Only a few longitudinal studies have examined the developmental pathways from childhood to the beginning of late adulthood.

The TRAILS study continues the Jyväskylä Longitudinal Study of Personality and Social Development (JYLS). The JYLS was initiated in 1968 and includes earlier data collected from ages 8 to 50. At age 61, in 2020–21, 206 of the JYLS participants (of the initial 369 children) took part in TRAILS. The data collection included a Life Situation Questionnaire, a psychological interview, self-report inventories, a health examination and physical activity surveillance covering major areas of adult life. TRAILS extends the JYLS study to over 52 years of follow-up time and provides unique opportunities for studying individual development throughout the lifespan.