What governments desire to achieve, and how they want to accomplish their goals, represent the core of any policy design process. However, it is still unclear how partisan politics, in its combined effect with pathdependency forces, influence policy makers' choices over alternative instrument mixes. Through a comparative analysis of Research and Innovation (R&I) instrument choices in countries characterized by different paradigmatic models of policy (Italy and France), the paper investigates how the politics of different cabinets influence the formulation of national R&I strategies and the extent to which these decisions are constrained by the legacy of previous choices. By capitalizing on a new proposed treatment of policy instruments, the paper contributes to the definition of the types of tools found in policy mixes, investigating how national R&I instrument mix variations develop. The results of the analysis indicate how the selection of R&I policy instruments does not closely follow traditional left versus right-wing political cleavages, and their evolution is generally influenced by a combination of different context-dependent dynamics. However, when partisan acceptance of consolidated R&I instrument mixes across cabinets is present, this triggers a consolidating effect on pathdependency forces.