The document discusses principles and criteria for evaluating computer-assisted language learning (CALL) materials and tasks. It outlines three needs that must be addressed in evaluation: incorporating research findings on second language acquisition, developing theory-based evaluation criteria, and providing guidance on applying the criteria. It also describes two perspectives for evaluation - judgmental analysis of software/tasks and empirical analysis of learner performance. Key criteria for evaluating CALL tasks discussed are language learning potential, learner fit, meaning focus, authenticity, positive impact, and practicality.