The ALPVD2 DYNAMO 3 program is a tool for demographic projection that is particularly suited to work with developing countries. The program transforms quinquennial population data into annual figures and can be used in entire countries or regionally. The annual data allow year by year population projections, minimize the bias due to using larger periods and eliminate errors of interpolation, and allow results pertaining to subgroups to be analyzed. The program calls for selection of 1 or more model life tables from which it extrapolates mortality quotients by age and sex. The program gives the total for each age and sex group for the beginning of each year. Several tables of mortality by sex can be employed during the same simulation; examples of 2 such procedures are given. Calculation of general fertility rates is accomplished after entering the average number of children, mean maternal age at birth, and variance around mean maternal age. Migration is introduced by supplying the stocks of emigrants and immigrants by sex, and can be constant, variable, or proportional. The program was applied to data from Guinea in 1970, when the population was approximately 3.8 million, with high mortality, an expectation of life at birth of 42.7 for females and 39.9 for males, average family size exceeding 6, and about 55% of the population under 20 years. 2 projections were prepared, 1 assuming continued high fertility and mortality and the other lowered fertility and mortality. Differences in the projected fertility totals to 2080 do not assume importance until after 2020; the 2080 totals under the 2 assumptions are 52 million and 21.37 million. The results from Guinea exemplify the possiblities of modeling with the program and indicate the consequences of typical population dynamics.