Marriage patterns of California's eighteenth and nineteenth century Spanish-Mexican families are analysed using data from genealogies and mission records. A shortage of women among the military based colonists led to an unusual marriage pattern with a large age differential between husbands and wives. The average age at marriage was 18·4 years for women and 28·4 years for men. Spatial mobility was high for both sexes, particularly for men. More husbands than wives were born in Mexico. The Monterey presidial district of central California was the birthplace of a disproportionate number of husbands and the southern California districts were a source of wives. The transition between a founding population predominantly composed of Mexican immigrants and a population of native-born Californians occurred at the beginning of the nineteenth century.