Public-private partnerships are a much misunderstood and still-evolving innovation in transportation infrastructure. Viewed with great suspicion by some as a ‘selling off’ of public goods, it is viewed with great enthusiasm by others as a source of additional revenues. In Massachusetts, we see public-private partnerships through the lens of recent projects that used private sector participation. This study seeks to examine several of those recent projects to learn about the private sector’s role and its impact on the project.