Comprehensibility is considered central to successful communication (Munro & Derwing, 1995a, 2007). Yet, despite the crucial role it plays in communication and the contribution it makes towards the assessment of spoken language ability, comprehensibility has occupied an ambiguous position in language testing. At times, it is feature-driven, taking a linguistically-atomistic approach with little reference to context or communicative purpose, treating comprehensibility as an abstract construct made up only of linguistic components. At other times, the assessment of comprehensibility is an intuitive action, relying on a holistic sense of understanding by the assessor and rarely going beyond the speaker's utterances to include listener characteristics. The lack of a perspective that encompasses broader linguistic and socio-pragmatic factors that contribute to achieving meaning in spoken language has motivated us to propose the current manuscript as an approach to understanding, defining and assessing comprehensibility. In this monograph, we argue that conceptualising comprehensibility as a multidimensional construct and adopting a broader perspective to understanding and analysing it for communication purposes would benefit the fields of second language assessment and second language acquisition.Parvaneh Tavakoli is a Professor of Applied Linguistics at the University of Reading. Sheryl Cooke is an Assessment Researcher with the British Council Assessment Research Group.