Private parties, who are usually involved in later stages of design, construction and maintenance, can potentially strengthen the early plan-making stages of infrastructure planning. They can bring in knowledge, expertise and experience to help address complexity in planning. Such early private involvement can be accommodated through several models for which experiences in Dutch infrastructure planning practice differ. In this article, we assess the potential of early private involvement for strengthening infrastructure plan development by examining evaluative studies and conducting interviews with public and private actors involved in four early private involvement models in Dutch infrastructure planning: market consultation, early design contest, market reconnaissance and unsolicited proposal. We conclude that in order to unlock the potential of early private involvement government needs to incorporate incentives for creativity, reward private involvement and strike a balance in the setup of the investigated models between conceptual freedom for private solutions and transparent public guidance in preconditions and regulations. Early private involvement could, thus, provide opportunities for conceptual creativity and innovation and opportunities for public-private collaboration, which can strengthen plan development.