Contemporary CALL research reflects renewed interest in digital games. One aspect of this phenomenon namely, use of massively multiplayer online role-playing games (MMORPGs), has expanded significantly, highlighting the need for a review. This paper analyzes findings from 10 learner-based studies that draw on accounts of SLA informed by cognitive and sociocultural theories. Analysis reveals that research conducted from the sociocultural perspective provides evidence of constructs identified as playing a central role in SLA. Analysis indicates that playing MMORPGs elicits target language dialogue involving collaboration, assistance and co-construction. Data show that MMORPGs provide access to conditions conducive to the operation of zones of proximal development. Findings show that this type of game provides access to both in-game and extramural communities of practice that facilitate language socialization. Research undertaken from a cognitive perspective shows that participation in MMORPG-based gaming facilitates production of the target language. However, this work does not provide conclusive evidence that game play elicits forms of interaction such as negotiation, that are hypothesized as playing a central role in learning in the cognitive account of SLA. Studies conducted from both perspectives draw attention to positive learner attitudes indicating high levels of motivation. The analysis reveals that although studies are subject to limitations, they have produced promising results. This suggests that further theory-led work in this area is justified, as it offers the prospect of making a significant contribution to the research base. As work continues, areas of potential interest in praxis, theory and future research are identified.