The influence of Age of Onset (AO) of Second Language Acquisition (SLA) on learners‟ Ultimate Attainment (UA) potential is well documented. The issue of Second Language Acquisition (SLA) potential enters a qualitatively different, pragmatic dimension in most multilingual developing nations (including Papua New Guinea), where English, a second language for most children, is also the language of education, and where, consequently, students‟ English proficiency necessarily affects their academic potential and the quality of their education. This study investigates whether the academic performance of students in the School of Humanities and Social Sciences (SHSS) University of Papua New Guinea (UPNG) is affected by their linguistic backgrounds. Specifically, we examined the effect of three factors in the students‟ Early Language Education – their Age of Onset of learning English (AO), their Age at Literacy (AGELIT), and their Early Learning Language (ELL) – on their Semester 1, 2017 Grade Points Average (GPA). A purposive cross-sectional sampling method was used for the selection of students. All full-time registered students in the SHSS during the 2017 academic session were eligible to participate in the study. A self-designed pretested questionnaire consisting of nine short questions was used to collect data on SHSS students‟ language education backgrounds, including their AO, AGELIT and ELL. Our results show a strong and statistically significant inverse correlation between students‟ AO/AGELIT and their GPAs, as well as a strong positive link between ELL English and students‟ GPAs, which contrasts sharply with a significant decrease in GPAs in the presence of ELL Tok Pisin. The ELL Vernacular category was too small (sample size N=34) to yield statistically significant results. Our current results corroborate the findings of our earlier studies which established a highly significant inverse correlation between students‟ AO and their academic performance in the National High Schools, as well as in the University of Papua New Guinea.