This book explores the construct of language in use, specifically as operationalised through different item types in the Austrian Matura (school-leaving exam). Empirical research on some of these item types is scarce. The author reports on a mixed-methods study. The theoretical frameworks employed are Purpura's (2004) model of language ability and Weir's (2005) socio-cognitive framework. The findings suggest that the tasks under investigation assess grammatical form and meaning at the sub-sentential and sentential level. Different item types were also found to target different elements of lexicogrammatical competence. The study contributes to understanding the nature of language in use and sheds light on the application of the socio-cognitive framework to the validation of language in use tasks.