The present study describes the relationship between three individual predictor variables and the degree of occupational expertise of middle and higher-level employees in three different career stages working in small and medium-sized enterprises (SMEs). Occupational expertise is operationalised by means of five dimensions, i.e. knowledge, meta-cognitive knowledge, skills, social recognition and growth and flexibility. The predictors in question are: the degree of participation in social networks, the degree of participation in training and development programmes and the degree of initiatives that are taken by the individual employee. Hypotheses have been tested with original survey data from 233 higher-level employees and 217 direct supervisors.