The delivery of quality primary health care (PHC) services can have a large impact on the health of Nigerians. This study aims mainly at understanding the performance of primary health care providers and the variables driving this performance. The study is primarily based on quantitative surveys at the level of primary health care facilities, health care personnel, and households in their vicinity. These surveys were implemented in four states: Bauchi, Cross River, Kaduna, and Lagos. The purpose of this study is three fold: (i) to contribute to the evidence base of the Federal Government's health system reform efforts; (ii) to inform the Bank's and Canadian International Development Agency (CIDA) sector policy dialogue with the Government; and (iii) to inform the current and eventual health support programs of both donors at state level. This study represents the second phase of the Nigeria Health, Nutrition, and Population Country Status Report (CSR). The first phase aimed at analyzing the health situation of the poor and how the health system was performing in terms of meeting their needs. This first phase identified primary health care as the weakest chain in the entire health sector and the level of care the poor use the most. This second phase of the CSR is therefore focused on the analysis of the delivery of PHC services. In contrast to the first phase, this study is mainly based on primary data, data collected through facility, health personnel, and household surveys. This study is focused in the collection of information not previously available, such as detailed roles and responsibilities of the Local Government Area (LGA) and states and community perceptions of PHC services. This study is also to support on-going or eventual health support programs of CIDA and the World Bank at the state level.