A review of the mating systems of 122 relatively well-studied European passerines (out of 172 species) is given. Of all species, 39% are polygynous and 25 of the 47 polygynous species are regular polygynists exceeding the limit of 5% polygyny in a population. Of 46 polygynous species, 63% are monoterritorial (having a maximum of one territory), the rest being polyterritorial (having a maximum of more than one territory). Regular polygyny is more common among polyterritorial passerines. Polygyny is frequently found among species breeding in open habitats (marshes, meadows, pastures and low shrubs). Polyterritorial species tend to have tropical winter quarters more frequently than monoterritorial species do. Colonial breeding is absent from the polyterritorial group. Monogamous male passerines participate more frequently in feeding nestlings than their polygynous counterparts do. Regular polygynists tend to be sexually dimorphic in plumage more often than infrequent polygynous passerines, and polyterritorial passerines similarly tend to be plumage dimorphic more often than monoterritorial species. Sexual size dimorphism was more pronounced in monoterritorial than in polyterritorial passerines.