The thesis evolved out of an experience of working for, or being involved with, Catholic agencies devoted to implementing humanitarian and long-term development programmes over three decades (‘Roman Catholic Faith-based Organisations’, RCFBOs). In the encyclical Populorum Progressio (1967), Pope Paul VI called for an ‘authentic development’ which would result in a shift for the poor from living in inhuman conditions to more human ones within their culture. Paul’s contribution to the debate about development was to insist that development was not just about the economy but had to be holistic and include the whole of life - social, political, cultural as well as religious. Since then, subsequent popes have built on Paul’s foundations such that a concept of Integral Human Development (IHD) is now firmly placed within the corpus of Catholic Social Teaching (CST), the ‘official’ Church teaching on issues affecting life and society. Some Catholic agencies have taken the concept of IHD and incorporated it into their work and praxis in the field. The thesis aims to delineate a fuller hermeneutic, or theological understanding, of IHD for both RCFBOs and the institutional Church. IHD lacks explicit definition by the magisterium (teaching authority) of the Church, and does not take into account the praxis of the agencies mandated by bishops’ conferences, and indeed the Holy See, to implement IHD programmes in the field. To delineate a fuller hermeneutic of IHD, I researched the teaching on one of the central tenets of the Catholic faith, diakonia, serving or ministering to the poor, in Scripture, Tradition and CST. Over four chapters (three to six), I construct a hermeneutic of IHD, and examine it in the light of RCFBO praxis. I found that the occasional mutual antagonism of Church and agencies was caused largely by ignorance of Church teaching on the part of RCFBOs (as well as among some priests and bishops) and by the lack of knowledge of, and exposure to, RCFBO praxis on th