One of the strands in the growing scholarship on political advisers in parliamentary democracies proposes that advisers can reduce the risk of civil service politicization by furnishing partisan advice to ministers, freeing civil servants to focus on the provision of expert competence. This benign narrative generates a significant hypothesis, which is that the institutionalization of the partisan role diminishes the risk of civil service politicization. That hypothesis has yet to be fully tested. Several studies have assessed the impact of advisers' actions on civil service impartiality, but the consequences of bureaucrats' own agency for that dependent variable have received far less attention. Drawing on data from a survey of New Zealand public servants, this article challenges the assumption in the political advisers literature that civil service politicization is primarily driven by exogenous factors and calls for a more nuanced theoretical approach to endogenous aspects of politicization.