The notion of `learning through doing' has been a guiding principle of cognitive therapy since its inception (Beck, Rush, Shaw, & Emery, 1979). The guiding principles of `outward focus' and `collaborative empiricism' require that we consider the therapy room analogous to the laboratory, and that the everyday situations and relationships in which the patient's problems exist represent an opportunity to gather data to test beliefs (Blackburn & Twaddle, 1996). In this way, homework extends what was discussed in-session, and provides an opportunity for data collection, skill practice and maintenance, as well as evaluation of situational, crosssituational, and core-level beliefs. Homework is a core and not an optional part of cognitive therapy. The implication is that a therapy that does not include homework cannot be considered cognitive therapy (Thase & Callan, 2006).