Background: Adolescence is a crucial point in life where choices, behaviors, and environmental influences can significantly shape future outcomes. This research investigates the increasing concerns surrounding adolescent substance use and examines its long-term effects on socioeconomic status (SES) in adulthood. Substance use during adolescence has been shown to have significant long-term physiological impacts, as the brain is still developing at this age. Additionally, many short- and long-term effects are associated with substance use, such as impacts on academics, physical and emotional well-being, and social life. Several studies have been conducted to explore the relationship between substance use and SES, however, there is little research that investigates how the initiation of substance use during adolescence will affect SES-related factors in adulthood while using a nationally representative sample and a comprehensive range of substances. Methods: Data from Wave I and Wave V of the nationally representative data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) dataset was used to explore the relationship between early initiation of substance use and subsequent socioeconomic-related outcomes during adulthood. Substance use was defined through survey questions addressing the age of initial exposure to alcohol, marijuana, and other illicit drugs reported at Wave I (ages 1-21), while SES in adulthood was assessed through objective indicators (personal income, educational attainment, and poverty indicators such as being unable to pay utility bills) and the subjective MacArthur Scale of Subjective Social Status (SSS) reported at Wave V (ages 33-43). Logistic regression was used to estimate odds ratios and 95% confidence intervals for the association between age at first substance use for each substance [categorized as never used (referent), first use at age 1-11, age 12-17, or 18 or older] and each adulthood SES outcome accounting for the complex survey design. Results: Age of first alcohol use was not significantly associated with adulthood functional poverty indicators, educational attainment, or personal income relative to the federal poverty line. Compared to those who never used, early alcohol use initiation was found to be strongly associated with a decreased SSS (first use at age 1-11, OR = 1.66, 95% CI = 1.08, 2.55). Age of illicit drug use initiation was significantly associated with functional poverty indicators in adulthood (age 12-17, OR = 1.40, 95% CI = 1.02, 1.90) and lower perceived SSS (age 12-17, OR = 1.56, 95% CI = 1.12, 2.27). Lastly, the first age of marijuana use was statistically significant across all measured outcomes, with differences present across age categories. For example, marijuana use was significantly associated with functional poverty indicators in adulthood (first use at age 1-11, OR = 3.40, 95% CI = 1.55, 7.49; first use at age 12-17, OR = 1.56, 95% CI = 1.30, 1.94), a lowered educational attainment (chi-squared = 69.3804, p = 0.0000), reduced personal income relative to the federal poverty line (first use at age 1-11, OR = 2.28, 95% CI = 1.06, 4.93), and a lowered perceived SSS (first use at age 12-17, OR = 1.39, 95% CI = 1.12, 1.74). Conclusions: The insights from this analysis will be beneficial to the local community as they have the potential to benefit adolescents from a reduced socioeconomic status in the long term; it can inform intervention strategies, public health policies, and result in the formation of other initiatives to mitigate potential consequences of the initiation of substance use. Understanding the relationship between the initiation of substance use during adolescence and the resulting repercussions to socioeconomic status during adulthood is essential in crafting targeted and effective measures to support the well-being of adolescents and, by extension, the broader society.