Public corporate governance guidelines are viewed as a means to increase the transparency and efficiency of fully or partially state-owned organizations. Many OECD countries have thus introduced such guidelines over the past decade. We examine the effects of the introduction of corporate governance guidelines on the governance process and on government entities’ portfolio of holdings. The analysis comprises the procedural effects, measured by the level of control, and the resulting effects, measured by the structure of the portfolio, of corporate governance guidelines. The introduction of guidelines at the subnational level in Switzerland has led to a significant increase in government control. However, the effect on government entities’ portfolios is not obvious, as the introduction of guidelines does not necessarily lead to a reduction in the overall number of holdings of regional governments, an increase in the participation quota, or an increase in the proportion of public-law institutions in the portfolio.