This chapter examines how a three-dimensional translation quality assessment grid (based on error type, effect and criticality) can be used to assess student translation performance with three different tools (standalone TM system, speech recognition and post-edited machine translation). The study was professionally-oriented, using a technical English-language source text, short deadlines for completion of each translation, and professional quality criteria. Group and individual performance in the translation of five 500-word extracts were assessed for quality and efficiency, with and without translation tools, using our assessment grid. The factors affecting group and individual performance and possible correlations between tool and performance were studied. The potential usefulness of the grid as a fine-grained training and professional assessment tool is discussed.