"This paper contains an application of the orphanhood method for estimating adult mortality, based on information provided during the period 1888-1910 by the brides and bridegrooms of six parishes of the Central Valley of Costa Rica.... Using the Brass technique for estimating adult mortality from orphanhood and interpolating the resulting probabilities of surviving into... Coale and Demeny's regional model life tables, the life expectancy at the age of 25 years is estimated [at] 41 years for women and 40 years for men."  Mortality differences by region and social-occupational group are considered.  (summary in ENG)