Massively Multiplayer Online Game (MMOG) is a unique categorization of electronic game which allows thousands of players to play simultaneously through the Internet in the same virtual environment. A number of researchers have started to introduce the use of MMOG as a new generation of educational platform, allowing players to interact and to learn together through collaborative game-play. However, the answers for the occurrence of collaborative learning behaviour and the motivational drivers for learning collaboratively in a MMOG are still underresearched. Motivated by such concerns, this study tests a theoretical model to explain individual's intention to learn by peer motivations. The model employs motivational theories to propose two external motivational factors, namely peer intrinsic motivation and peer extrinsic motivation, and investigates effects of the two new constructs on MMOG players' intention to learn individually and intention to learn collaboratively by building on the cognitive learning theory. Based on a study with 94 valid current MMOG player responses, PLS analysis shows that peer intrinsic motivation to play has a significant positive influence on the intention to learn collaboratively, while peer extrinsic motivation to play has a significant positive influence on the intention to learn individually. The results of our findings indicate potential implications to researchers, educators and game developers.