This book highlights the use of indirect demographic methods to assess the quality of data obtained from the vital registration system of births and deaths in Mokola, a semi-urban community in Oyo state, Nigeria. Using a cross-sectional methodology and a structured questionnaire, the study elicited information from over a thousand households, including men and women aged 15 to 65 years living in Mokola. Analysis showed that completeness of births and deaths registration was very low and thus, largely incomplete. The study suggests the need to strengthen births and deaths registration system in Nigeria.