The RCA believes in Christian unity and expresses this belief by belonging to several "families" of churches. The Reformed Church is a member of the World Alliance of Reformed Churches and is a founding member of the World Council of Churches and the National Council of Churches of Christ in the U.S.A., and Christian Churches Together.
Additionally, the RCA has entered into a Formula of Agreement with the Evangelical Lutheran Church in America, the United Church of Christ, and the Presbyterian Church (USA).
The RCA also expresses unity by working in partnership with other denominations to publish resources, host training events, and coordinate special programs. The RCA's mission program operates through partnerships with other Christian churches and mission organizations.