Do parties matter for policy accumulation? An analysis of social policy portfolios in 22 countries

Expected effects on policy portfolio diversity in the environmental sector.


This article analyses the role of political parties in policy accumulation. We study this relationship in the area of social policy. Our analysis builds on a large data set covering the size of policy portfolios (policy targets and instruments) in three subfields of social policy for 22 OECD countries over 30 years. We find that the probability of social policy accumulation is not affected by the government’s ideological position. Left governments do not produce more extensive social policy portfolios than right ones. Yet, this striking result does not contradict governments’ political ideologies, as left and right parties accumulate for different reasons. While left parties address new social policy targets to broaden the scope of the welfare state, right parties adopt new policy instruments to condition social benefits. These findings hold regardless of how we measure governments’ ideological position and despite strong endogenous policy growth dynamics, that is, countries with greater policy portfolios also display higher levels of policy accumulation. Our findings indicate that party political considerations can explain the reasons for but not the level of policy accumulation. Changes in government are thus unlikely to stall or slow down the constant accumulation of public policies.

European Journal Political Research

Online appendix

The online appendix contains an extension of the procedures and results presented in the paper.

Code and replication material

The whole set of code and data for the replication is available at the Harvard dataverse (doi: 10.7910/DVN/7XJLJB).

Local copies are available for:

  • Report (1.7 Mb, 237 pgs), containing the main report in PDF with all the code.
  • Material (16 Mb), compressed file containing all the files needed to perform the analysis and generate the final report.