This multidimensional study looks at the influence of social capital and internal vs external locus of control on tacit knowledge-sharing intention and behaviour, and the relationship between the two. The relations studied within the framework of the proposed model are tested by regression analyses. The findings indicate that social capital and its basic structural, cognitive, and relational dimensions tend to increase tacit knowledge-sharing intention, which gradually turns into behaviour because, according to Ajzen's theory of planned behaviour, behavioural intention is the immediate antecedent to behaviour (or according to Ajzen's theory of planned behaviour, a person's intention to perform a behaviour increases as subjective norms become more favourable). It is further concluded that having an internal locus of control increases both the intentions and behaviour, whereas external locus of control only increases the behaviour. The study also concludes that tacit knowledge-sharing intention gradually turns into sharing behaviour. The study is considered to contribute to the field of knowledge management in various ways. In this study a multidimensional survey of 42 questions was used to investigate the research topic and its sub-dimensions, and the data were collected via face-to-face interviews. The population of the study was 106 nursing students, and all components of the research universe were reached. It was found that social capital positively affects and increases tacit knowledge-sharing intentions and behaviour. A research model based on the conceptual framework was developed and research questions were addressed by means of this model and the findings.