In the past decade, there has been a steady increase in the importance of collaboration to value creation in organizations, which has given rise to a new research field. Collaboration Engineering aims to model, design, and deploy repeatable collaboration processes to be executed by practitioners themsleves of high-value recurring collaborative tasks. Thus the aim of collaboration engineering is to create ready made designs for group processes. A key concept in Collaboration Engineering is a thinkLet - a codified facilitation intervention in a group process to create a desired pattern of collaboration. This paper presents an analysis of the thinkLet concept and possible thinkLet classification schemes to support collaboration engineers in effectively designing collaboration processes.