Wetlands are complex ecosystems, considered among the most productive environments in the world. They contain important biodiversity hotspots, provide the resources on which countless plant and animal species depend and perform important environmental and economic functions. Wetlands reduce flooding events, improve water quality and represent a valuable cultural and natural heritage. The European Directive (2000/60/EC) requires fostering an integrated approach to wetland management through collaborative governance processes. The Wetland Contract is a tool that has been developed and implemented in order to promote the sustainable governance of water systems. Among the Mediterranean countries, Italy and Croatia count on a rich variety of coastal wetlands that, together with the plants and animals that inhabit and pass through them, constitute an extremely valuable natural heritage. This paper presents and discusses the results of the Interreg Project CREW that, between 2018–2021, contributed to the drafting of seven new Wetland Contracts. Through a comparative reading, the aim is to understand, on the one hand, how the different Contracts have responded individually to a shared programme based on European requirements; on the other hand, the aim is also to bring similar experiences closer together to assess their overall potential on an international scale. The article shows how the constant exchange between CREW partners and the continuous updating on ongoing activities, methodologies and proposed solutions in the seven target areas facilitated the construction of a shared cross-border strategy for wetland governance. The comparison also highlights some principles considered fundamental by all partners (protection and enhancement; integrated governance; awareness-raising and learning) that have served the construction of a transnational Observatory, aimed at monitoring, sharing practices and able to guide the formation of future Wetland Contracts.