This deliverable reports on the results of the task “T.3.1: Current practices and state-of-the-art of Application Program Interface (API) consumption” of the work package (WP) 3 “API Consumption”. The goals of WP 3 are to develop and enhance techniques to guide and verify correct usage of behavioural APIs (b APIs) and their composition. The envisaged techniques include: automated compatibility analysis of b-APIs, inference of b-APIs from existing complex code (e.g., reverse engineering of b-APIs composition), and analysis of properties of complex compositions.