A widespread strategy to enhance political control over permanent bureaucracy consists of the politicization of personnel policy through the appointment of ministerial advisers. This study sets out to investigate the appointment of ministerial advisers from an historical institutionalist perspective emphasizing the influence of institutional legacies on current empirical patterns. Drawing on this perspective, it identifies three patterns of institutional stability, radical, and gradual change in terms of ministerial advisers’ policy competence and political loyalty, which guide the empirical analysis. Empirical patterns are illustrated with data collected in Italy, based on an analysis of a combination of career pathways and expert interviews. The Italian case is noteworthy since it experienced an abrupt party system breakdown in the early 1990s. Yet, the empirical analysis reveals that the massive re-alignment of the party system has not implied a pattern of radical change in Italy. The legacy of stable administrative structures has only left room for gradual change to occur on the dimensions of ministerial advisers’ policy competence and political loyalty.