In the field of Second Language Acquisition (SLA), the role of transfer has been theorized and studied to account for the influence of the native language on an interlanguage. However, stemming from behaviorist mentality, the concept of "transfer" has become widely associated with the direct transfer of habits and fails to take into consideration other cross-linguistic influences (CLI) that shape or are shaped by the interlanguage, such as avoidance, 'reverse transfer' from a learner's second language (L2) to native language (L1), "perception" of linguistic distance, and interlanguage transfer. Thus, the reductionist analysis of direct L1 to L2 transfer is no longer sufficient to account for the parallel activation of languages in multilinguals. To acknowledge the unique and complex cognitive development of multilinguals, a wave of research has been conducted to extend our theoretical perspective of CLI to include interlanguage transfer, the carryover of a linguistic feature from one interlanguage system to another. This research in third language acquisition (TLA), an offshoot of SLA that concentrates specifically on the acquisition of a subsequent language beyond the second, may enhance our understanding of cross-linguistic influences in particular and acquisition processes in general. A general theoretical overview will be presented in the first section of this paper in order to provide background knowledge of the current theories on the psycholinguistic factors involved in L3 acquisition. After establishing these theoretical foundations, the paper will then delve into a more in-depth analysis of some prominent studies on the topic of interlanguage transfer. In order to ensure a comprehensive view, the studies range and are organized according to the linguistic domains they assess beginning with a focus on the development of L3 phonology, followed by the development of L3 lexicon and morphology, and finally the development of L3 syntax. The findings from the studies discussed will then be coalesced in the final sections to develop an understanding of interlanguage transfer overall and its role in the broader field of SLA.