What determines whether interest groups choose to contact politicians or bureaucrats? Despite the importance of this question for policymaking, democracy, and some prominent principal-agent understandings of politics, it is relatively unexplored in the literature. We argue that government stability plays a major part in interest groups’ decisions. That is, central to interest groups’ decisions is their assessment of the likelihood that politicians currently in power will continue to be in the future. We deduce logical, but totally contrasting hypotheses, about how interest groups lobby under such conditions of uncertainty and then test these using a heteroskedastic probit model that we apply to a unique longitudinal survey of interest groups in Japan. We find that when it is unclear if the party controlling the government will maintain power in the future, interest groups are more likely to contact the bureaucracy. When it is believed that the party in power will retain control for a considerable period, interest groups are more inclined to contact politicians. In addition, during times of government uncertainty, interest groups that are supportive of the governing party (or parties) are more likely to contact politicians and those that are less supportive will be more likely to contact bureaucrats.