This paper looks at the use of institutionalised public‐private partnership (PPP) arrangements by local governments for the delivery of different types of infrastructure. It starts by analysing the mixed company model from a theoretical point of view, in particular the potential for internal regulation and the achievement of relational agreements. Then, after discussing the practicalities of crafting this type of governance structure, the examination of four Portuguese case‐studies is provided. The empirical evidence on mixed companies operating in the water, waste, transportation and education sectors shows that the extreme complexity involved in the whole life‐cycle management of these companies, usually leads to poor outcomes from a social welfare point of view.