This article analyses the transmission of policy priorities from electoral campaigns to legislative outputs under different institutional configurations. Taking an agenda-setting approach, the article tests whether a mandate effect exists, if incumbents also uptake the priorities of their competitors, and whether and how the introduction of alternation in government impacts on these dynamics. The analysis relies on data sets of the Italian Agendas Project recording the issue content of party manifestos and laws and covering the period 1983–2012. The results of time series cross-sectional models lend support to the presence of a mandate effect in Italy, a mechanism which was strengthened after the introduction of alternation in government. Opposition priorities may have an impact on the legislative agenda, but mostly when considering the legislation initiated in Parliament. Our findings have important implications for the understanding of the impact of government alternation, an institutional feature underlying – with varying intensity – most democracies, on the functioning of democratic representation.