This longitudinal study finds that spousal capital is an important resource for entrepreneurs starting a business because it has implications for business sustainability and couple relationship quality. Structural equation modeling supported a process whereby gender had an impact on spousal involvement in the business, which was positively associated with dedication to the business, leading to shorter break-even times, and higher couple relationship quality. Male entrepreneurs were more likely to have a spouse involved in the business compared to female entrepreneurs, which in part, may contribute to the gender gap in the success of new businesses. Study findings have implications for couples seeking to start a business as well as family educators working with such couples.