Enormous sums of money and human effort have gone into educational technologies over the past decade. Yet nagging questions surface as to whether this tremendous investment produces advantageous results. While we intuitively feel that the influence of technology should be substantial, little sound guidance exists as to what is effective and why or how to use it. We seem to have cleared several of the hurdles for building a computer-aided instruction infrastructure; now we must turn our attention to richer understandings of research into the impact of technologies in the classroom. This special issue of the Journal of Universal Computer Science focuses on assessment and evaluation practices. The six articles in this collection have been clustered around three major issues: (1) pragmatics - cost estimations and product reviews, (2) measuring the effectiveness of theory-driven design, (3) extending paradigms for capturing more profound understanding of variables and outcomes.