After explaining why consideration of the use of technology in second language (L2) teaching in the primary and secondary sectors is necessary, this systematic review presents a keyword map of 117 studies of technology in L2 learning since 1990. It reveals that research effort in these educational sectors has increased in line with technological developments and there have been important differences between the primary and secondary sectors in the adoption of applications. There then follows an in-depth review of 47 post-2000 studies investigating the efficacy of technology in the teaching of L2 English. It asks what technology has been used and why, what evidence there is that technology facilitates language learning, and what other insights can be drawn from the research in this field. The evidence that technology has a direct beneficial impact on linguistic outcomes is slight and inconclusive, but it may impact indirectly and positively on learner attitudes and behaviours and may promote collaboration. On the whole, the research reviewed lacked the quality that would reassure practitioners and policy-makers that technological investment is warranted. We argue that future research needs to provide a tighter link between technological applications, Second Language Acquisition (SLA) theory, and learning outcomes.