The cognitive advantage (CA) hypothesis claims that multilingualism promotes the development of several basic cognitive capacities. A large number of empirical findings support this hypothesis, but recently there have also been numerous contradictory findings and methodological objections. The present paper extends the investigation of possible cognitive advantages from basic cognitive (executive) functions to broader cognitive competencies such as cognitive flexibility. A promising candidate for this is 'flexibility of goal adjustment' (FGA), a capacity of developmental regulation that solves problems through flexible adaptation processes. In a study with N = 119 monolingual and multilingual adults we found the predicted positive correlation between multilingualism and FGA. However, the mediator function of executive capacities entailed in the CA hypothesis operationalised as Stroop and flanker tasks could not be demonstrated.