Passive sentences in Spanish come in different varieties and present complexity at the syntactic, semantic and morphological level. This study reviews research showing that child and adult heritage speakers of Spanish develop basic knowledge of these complex sentences early on, even when these are not very frequent in spoken input, but they may be less efficient than baseline speakers interpreting different word orders, gender agreement, the semantics of the by-phrase, and the aspectual interpretation of the copulas ser and estar. Accuracy with the production and comprehension of passives is related to proficiency in the heritage language, and literacy experience enhances the acquisition of all the complexities of verbal passives in Spanish