Efforts to examine the role that dispositions play in cognitive activity are likely to be repaid in understanding further how individuals think, act and develop. This paper discusses theorising and empirical work which proposes that the dispositions underpinning cognitive activity need to become more central to deliberations about how individuals think about and engage in skilful vocational practice. Such activity has consequences for how and what is learnt as well as individuals' ongoing development. Central to the analysis provided in the paper is a consideration of Nunnaly's (1976) classification of dispositions as interest, attitude and values. Having reviewed ideas about the dispositional underpinnings of skilful knowledge, the paper reports a study examining how individuals construct knowledge associated with their vocational practice. This study provides tentative findings about the source of dispositions and their role in vocational activity. From these findings, it is claimed that dispositions are socially sourced through individuals' histories and their participation in communities of practice. It is proposed that these sources influence thinking and acting and, hence, cognitive development. Hence, the dispositions which influence how individuals think and act are sourced socially. The paper concludes by advancing some implications for instruction.