Individuals match on length and type of education. We investigate whether the systematic relationship between educations of partners is explained by opportunities (e.g. low search frictions) or preferences (e.g. complementarities in household production or portfolio optimization). We find that half of the systematic sorting on education is due to low search frictions in marriage markets of the educational institutions. The other half is attributed to complementarities in household production, since income properties of the joint income process show no influence on partner selection.