Assortative mating is the mating of pairs that are more similar in some trait than would be expected from random mating. It takes place when sexually reproducing organisms tend to mate with individuals that are like themselves in some respect (positive assortative mating) or dissimilar (negative assortative mating). The present study measures verbal and nonverbal intelligence, along with several temperamental traits, testing the similarity, complementarity, social homogamy, and convergence hypotheses. The role of marital satisfaction was also analyzed. The sample comprised 357 adults (age range 19-69), who completed verbal aptitude, inductive reasoning, and temperament tests. The findings show that couples are similar in almost all the measured traits, even after controlling for age and educational level. Differences were observed in the couples' degree of similarity depending on the duration of their relationship. Further, only similarity in verbal intelligence for males and in impulsivity for females was associated with marital satisfaction in long-term couples.