We offer fresh evidence on the effect of migrant networks on two essential aspects of migration: (1) the total scale of migration and (2) the skill composition of migration. Our analysis is for the remarkable case of Spain, which experienced a full‐blown immigration boom from the mid‐1990s up to the Global Financial Crisis. To accommodate flexible substitution patterns across alternative migrant destinations, we use a three‐level nested multinomial logit model. We find a strong positive network effect on the scale of migration and a strong negative effect on the ratio of high‐skilled to low‐skilled migrants. Simplifying restrictions on the structure of cross‐destination substitutability are rejected by the data. (JEL F22, J61)