The paper proposed focus on the underspecified role of instruments in the theories explaining policy dynamics. In order to obtain a better understanding of the dynamics of public policy and, more specifically, whether changes in instruments lead to substantive or minor policy change, the paper postulates the need to consider their role within the configuration of meanings and assumptions formed by the different components of policy designs (Schneider and Ingram 1997). Particularly, it is argued that the contribution of changes in policy instruments to substantive policy change would depend on the degree the meaning attributed to such instruments is central to the coherence of assumptions and justifications underlying the policy design shared by policy participants. This is shown through the case of the Spanish research training policy, where the issue of substantive policy change has been mainly associated to the instruments to be used.
