An understanding of past, from which we learn, and present, through which we observe, population dynamics is necessary for development planning for a country. This paper studies this present facts of and past trends in population dynamics paying particular attention to the major demographic variables of population, fertility, mortality, and migration profiles in the last two decades with an assessment of various demographic data sources in Bangladesh. In doing so various literatures were reviewed and secondary data were generated mostly from international sources, like database of the United Nations, Population Reference Bureau, US Census Bureau etc., and partly from national sources, like population census, Bangladesh demographic and health survey etc., which are the major sources of demographic data for Bangladesh. The study observes that the demographic indicators of Bangladesh have shown considerable development during the last two decades. Though the population increased in size but growth showed a declining trend. The total fertility rate declined from 3.96 children per woman during 1990- 1995 to 2.36 during 2005-2010, and infant mortality and under-five mortality rates almost halved during the same period. Life expectancy at birth recently reached to 69 years from 56 years in 1990. Moreover, international outmigration showed an increasing trend with a very low rate for female.