In this paper I identify the factors that can skew the result of two standard unaccusativity diagnostics in Russian (distributive po-phrase and verb prefixation): (i) animacy of the subject (ii) verbal aspect. I introduce a new class of data, which reveals a contrast that is characteristic of all unaccusative predicates: Experiencer/Theme interaction. Unlike the well-known agentivity effects (Permutter and Postal (1984), Hoekstra and Mulder (1990), Zaenen (1993)), Experiencer/Theme interaction is linked to animacy, but not to volitionality. The connection between animacy and an Experiencer is formalized as an Experiencer condition: the Experiencer role must be assigned if the sole argument is animate. I propose a novel view of argument distribution whereby animate arguments can be base generated VP-externally. Variable applicability of unaccusative tests to telic/atelic verb forms results from the interaction between the Experiencer condition, the structural view of telicity (Folli and Harley (2005), Ramchand (2008)) and world knowledge.