The decline in mortality in Taiwan since World War II is analyzed using life tables. "Special features of the research include (1) a phase-of-life-specific, rather than an age-specific, analysis of mortality, and (2) the use of measures based upon person-years of life in phase intervals, rather than survival rates or expectation of life at given ages.  The empirical results suggest that the mortality decline can be described as a two-stage process:  an initial stage of substantial improvement in life expectancy between 1950 and 1965, and a final stage of slow gain in life expectancy since 1965."  Age and sex variations in mortality and differing rates of mortality decline are noted.  Implications of increased longevity for economic and social programs are also considered.  (summary in ENG)