The purpose of this paper is to describe the pattern of population growth during the period of socio-economic development, 1905-1976. This analysis lookks at population trends for two broad periods: (1) the period of agriculture from 1905-1942, and (2) the period of development from 1946-1976. This latter phase is examined in terms of (a) the initial period of societal development (1949- 1960), and (b) the most recent period of transition from 1961-1976. It was found that following the transformation from an agrarian to an urban-industrial society, the population has undergone a transition, but the transition of both fertility and mortality exhibited a different speed and pattern in the stages of socio-economic development. In the initial stage, a moderately high birth rate rose even higher while mortality decreased. If we look at the demographic transition in terms of declining mortality, it may be said that the population was in transition from about 1910 onward. But this mortality deceline was more in keeping with the Malthusian model rather than transition theory; and it was not until 1956, when socioeconomic development began to have an effect on social structure, that birth rate declines took place. As societal development went further, the birth rate decline accelerated while the deth rate decline slowed down, and the population seemed to be approaching a new demographic balance between low birth and death rates. The lag between the transitions of mortality and fertility decline was only about 50 years in Taiwan, as compared to 100-200 years in most modern European countries.