Ireland is a latecomer to public–private partnerships, having only adopted them in 1998. Prior to the credit crisis, Ireland followed the UK model, with public–private partnerships being implemented in transport, education, housing/urban regeneration and water/wastewater. Having stalled during the credit crisis, public–private partnerships have recently been reactivated with the domestic infrastructure stimulus programme. The focus of this article is on Ireland as a younger participant in public–private partnerships and the nexus between adoption patterns and the sustainability characteristics of Irish public–private partnerships. Using document analysis and exploratory interviews, the article examines the reasons for Ireland’s interest in public–private partnerships, which cannot be attributed to economic rationales alone. We consider three explanations: voluntary adoption – where the UK model was closely followed as part of a domestic modernisation agenda; coercive adoption – where public–private partnership policy was forced upon public sector organisations; and institutional isomorphism – where institutional creation and change around public–private partnerships were promoted to help public sector organisations gain institutional legitimacy. We find evidence of all three patterns, with coercive adoption becoming more relevant in recent years, which is likely to adversely affect sustainability unless incentives for voluntary adoption are strengthened and institutional capacity building is boosted.