In this monograph the author probes the fundamental nature of the concept of agency and its importance to human language and cognition. Whereas previous studies focused on grammatical manifestations this original work addresses such issues as the strong relationship between agency and responsibility, a philosophical interpretation of the concept of agency and a variety of epistemic attitudes towards agency that strongly influence our view of the world. Different cultures and languages process and express agency differently. To illustrate the co-relation between the linguistic expressions of agency and cultural stereotypes that lurk behind individual natural languages, the author analyses Japanese and English parallel corpora. It is shown that English tends to highlight agency in expressing actions and events, whereas Japanese largely obfuscates agency through impersonalising potential agents. Through the case studies on these languages this book sheds light on the close connection between language, thought and culture and contributes to the resurging interest in linguistic relativity.