Vulnerable consumers are at particular risk of financial detriment due to, for example, low financial literacy or numeracy, high debt, low income, or impactful changes in personal circumstances. We introduce a comprehensive and formative measure of financial vulnerability that integrates these risk factors and is grounded in definitions of vulnerability from financial regulation bodies and government agencies such as the Consumer Financial Protection Bureau. Across three studies of US individuals, we assess the nomological validity of this measure of financial vulnerability through its relationship with positive and negative financial outcomes (e.g., savings levels, paying credit card balances in full each month, being in arrears) as well as relevant psychological characteristics (e.g., personal savings orientation [PSO], money management skills, financial self‐efficacy). Moreover, we examine whether and how these psychological characteristics mediate the relationship between financial vulnerability and financial outcomes. We conclude with an overview of implications for policy makers and business practitioners.