Processes of Adaptation in Intimate Relationships Project: one of the earliest and most influential longitudinal studies of marriage. The PAIR Project followed 168 Pennsylvania couples from their newlywed days to 14 years after marriage. Its initial goal was to examine how social and psychological factors present in courtship would predict adaptation to marriage. Later studies examined these and other factors as predictors of marital deterioration and divorce. See also Early Years of Marriage Project. [begun in 1981 by U.S. psychologist Ted L. Huston]