In recent years, an emerging stream of literature has focused on instrument selection as a driving question in policy design and public policy studies. Hence, scholars have devoted increasing attention to the political, institutional and cognitive dimensions that influence decision-makers when choosing a policy instrument based on their preferences and the contextual pressures. On this issue, a recent typology assumes that two main factors determine the process and assessment of instrument selection: legitimacy and instrumentality. Given the boundaries created by how decisionmakers perceive these two dimensions, decision-makers can show only four selection patterns: hybridization, stratification, contamination or routinisation. The article aims to assess these four patterns by applying them to a diachronic analysis of instrument selection in Italian education policy for the 20-year period from 1994 to 2016.