Much knowledge on which performance in practice is based is tacit (Smith, 2001) making it a valuable, rare resource, which is difficult to imitate or substitute (Barney, 1991) and a vital source of organisational competitive advantage. However, there is limited research available delineating tacit from explicit knowledge (Insch et al., 2008; Perez & Mitra, 2007) and thus gaps in our understanding about how to derive the greatest value from it. Knowledge management (KM) is partly a socially constructed phenomenon embedded in people and relationships (Nonaka, 1991). However, KM research has neglected the role of the micro-level of individuals and social interactions (Foss, 2009). Furthermore, knowledge sharing research neglects to explore all phases of what is a bi-directional relationship. Scant research exists on the knowledge seeking process- from the seeker to the source (Hansen, Mors & Lovas, 2005) as the focus is on the uni-directional notion of knowledge sharing- from the source to the seeker (Kim, Song & Jones, 2011). This study utilises the social capital lens, which focuses on social relationships and in particular the relations between, rather than the characteristics of, individuals, groups, processes, or organizations, to explore tacit knowledge seeking processes. The data is based on five American multinational manufacturing organisations and interviews with 105 operators, technicians and engineers engaged in tacit knowledge work. The paper discusses the results of the investigation of the relational social capital factors of trust, norms, sanctions and social identification and their influence on decisions to operationalise a tacit knowledge seeking interaction.