The Christian Church has undergone a process of institutional transformation since its establishment almost two thousand years ago. This transformation has changed an originally fluid and charismatic organisation into an hierarchical one, with its leadership (Roman Catholic) entrusted only to the ordained clergy. This type of Christian Church brought to Nigeria by the early catholic missionaries has both its advantages and disadvantages. Among the advantages is the increasing membership of the Roman Catholic community and the increased production of indigenous priests. However, the strategy of early missionary evangelisation marginalised the role and effectiveness of the Catholic laity in Church activities. Thus, the management of the Church as an organisation is wholly in the hands of the ordained. However, the continued worldwide decline in the recruitment and number of priests, and the unfavourable priest-to-laity ratio - particularly in Nigeria - both indicate a need for a change. Furthermore, the influence of both celibacy and contemporary social factors (for example, the unwillingness to enter a life-long relationship that priestly and religious life demands), and the innovation which the Second Vatican Council advocated all cast doubt on the viability of the continuation of the status quo. These issues, therefore, make - greater, involvement of the Christian faithful in Church management and leadership inevitable, particularly in those countries like Nigeria where the demand for priestly ministration is on the increase, and the laity are increasingly willing to use their pneumatic gifts within the Church. These (pneumatic gifts) are the spiritual and other gifts received by baptised members, and include preaching, administration and prophecy. It is the manner of the laity's involvement on the universal and arch/diocesan levels that are explored in this thesis. The thesis also examines the major factors that contribute to the shortage of priests, and candidates for priestly and religious life, and explores the arguments for and against the continuation of the existing ecclesiastical law of clerical celibacy. Some recommendations are suggested that could ensure that the Roman Church continues to be relevant in the contemporary time to Catholics everywhere both on the universal and arch/diocesan levels. For the archdiocese of Lagos, Nigeria, the need to reorganise the archdiocesan structure is highlighted, as is the possibility of introducing some 'new' ministries particularly to involve the many pneumatically gifted laity is offered. Finally, it is argued that if the initiatives engendered by the Second Vatican Council were followed through, the conclusions and recommendations arrived at in this thesis are inevitable, and the Roman Church could either generously initiate these changes now or allow the changes to force themselves upon the Church in the future.