This book presents a synchronic study on the applicability and the acceptability of the passive and three impersonal constructions in Polish (-no/-to, reflexive, and 3pl) and Russian (3pl construction) that were contrasted with a regular active construction. The constructions show different degrees of applicability with different verbs independent of the animacy of the demoted subject. The main idea pursued in this book is that the grammaticality of the relevant constructions depends on the degree of agentivity of the implicit subject entailed by the verb. For the description of the verb semantics Dowty's proto-role model (1991) is used, which operates by summing up the proto-agent, and the proto-patient entailments to determine how much 'agent-like' or 'patient-like' a semantic role is.