How bilinguals switch between languages depends on the context. In a voluntary context, bilinguals are free to decide when to switch, whereas in a cued context they are instructed when to switch. While using two languages may be more costly than using one in cued switching ('mixing cost'), recent evidence suggests that voluntarily using two languages may be less effortful than using one ('mixing benefit'). Direct comparisons between mandatory and voluntary switching, however, are needed to better understand the effects of the interactional context on bilingual language control. The current study compared mandatory and voluntary switching within the same task, thus keeping the overall task characteristics the same. We observed overall slower mandatory responses and larger mandatory than voluntary mixing and switching effects. Thus, using two languages is more costly in a mandatory than voluntary context, showing that the interactional context can affect the effort needed to control two languages.