Declan Ronan Lang (born 15 April 1950) is an English prelate of the Roman Catholic Church.

He has been particularly noted for the influence he had as a youth chaplain and subsequently on those now playing leading roles in the Catholic community such as the evangelist and charismatic Catholic Sr Maria Natella OP and the ministerial adviser and author Francis Davis; and also for his work as an adult educationalist and as an ecumenist.

He then served as an assistant priest at the cathedral and chaplain to St Edmund's comprehensive school in Portsmouth.

As a result of his work in adult religious education he produced together with John O'Shea, Vicky Cosstick and Damian Lundy the book Parish Project.

The Working Party Report was accepted by the Bishop's Conference and since then he has spoken in a number of dioceses about the reasons for and the benefits arising from clergy appraisal.

He is a member of the Mixed Commission of Bishops and Major Religious Superiors and is a trustee of the Pontifical Missionary Societies.

Outside the Bishops' Conference he is the President of the Catholic Association which organises a pilgrimage to Lourdes on behalf of the Dioceses of Clifton, East Anglia, Northampton, Portsmouth and Southwark, and of Stonyhurst College.