Social networks play an important role in the employer–worker match, and the social capital perspective has been used to understand how social networks contribute to labour market inequality. This paper investigates the effect of social capital on achieving a stable labour market position for young adults, examining how boosted job finding self-efficacy is a possible mediator. The paper also examines whether social capital and self-efficacy are related to the preferred job search method. The study utilises a Swedish survey of young adults that is linked to tax register data on earnings. Here, social capital is defined as an extensive network and measured with the position generator, asking about knowing contacts in various occupations. The paper analyses heterogeneous effects that depend on the respondents’ initial status regarding employment and job search. The results show that social capital and job-finding self-efficacy are positively related to achieving stable employment for the initially not employed job searchers, but there is no effect for those initially employed and not searching for a new job. Furthermore, an analysis of job search methods reveals that social capital is positively related to preferring social networks and direct application and negatively related to searching through public employment services. The results also indicate that self-efficacy mediates only a little of the relationship between social capital and prospective employment, suggesting that job-finding self-efficacy likely only contributes slightly to how social capital affects labour market outcomes.