Off-line computer-assisted vocabulary trainers have been available to the general public since the 1980s, on-line trainers started to emerge 20 years later. With the advance of technology their databases, design, and tools supporting language learning have been changing continuously and choosing a trainer suitable to one's learning situation, needs and goals can be a tricky task. To these ends, 6 off-line and on-line computer-assisted vocabulary trainers for native speakers of German learning English as a foreign language were examined, all developed between 2003 and 2009 by LEO and the publishing houses Koch Media, Digital Publishing, Langenscheidt, and Pons. This study analyzes how vocabulary is introduced to learners, how learners can practice vocabulary, what feedback is provided, what kind of assessment takes place, and how software programs guide learners through the entire learning process. Possible improvements are suggested and meant to help establish guidelines for the future development of innovative vocabulary trainers.