Upward intergenerational mobility is often viewed as a sign of social progress and individual achievement because moving into a higher socioeconomic position can improve access to education, income, occupational opportunities, and other useful resources. These changes may reduce exposure to material hardship and, in some cases, support better psychological well-being. At the same time, upward mobility is not always psychologically beneficial. The effort to attain a higher socioeconomic position often involves prolonged stress, strong performance pressure, repeated social comparison, identity-related tension, and fear of falling behind. In addition, not everyone who strives for upward mobility succeeds. Even when objective gains are made, individuals may still experience psychological strain linked to relative deprivation, feelings of inadequacy, distance from their family or community of origin, and continuing insecurity about their social position. This narrative review examines both the possible benefits and the less visible mental health burdens of upward intergenerational mobility from a lifespan perspective. The current study proposes a developmental framework that distinguishes resource-related benefits from mobility-related psychological costs, with particular attention to aspirational strain, uncertainty, comparative stress, belonging conflict, and the emotional consequences of perceived failure or insufficient progress. A central argument of this review is that the mental health implications of upward mobility depend not only on objective socioeconomic gains but also on how individuals interpret their movement, compare themselves with others, and negotiate identity and belonging across the life course. The review concludes with implications for research, practice, and policy, emphasizing that upward mobility should not be treated as a uniformly protective process for mental health and that efforts to promote mobility should also take account of the emotional burdens attached to it.