The general aim of the study is to describe and to try to understand the population development (mortality and fertility) in Ovamboland in North-Namibia. Parish records are used as a primary source. The family reconstruction method based on marriage cohorts has been used. The data includes about 7,000 marriages and 27,000 children. Administrative and missionary records were used especially in interpretation of research results. According to the results both a clear decline and increase in fertility have occurred during 1930-1980 although fertility has been all the time close to natural fertility. Mortality declined in the 1950s in Ovamboland. The main cause for the mortality decline was probably the health care system built by the missionaries. At the same time, however, there was no more bad famines in the area during the 1950s and in general the nutrition level also improved during the 1950s