The current study investigated the correlation between English collocation test scores and three independent variables including vocabulary level, informal language exposure, and motivation. The study also examined which independent variable was the most influential in predicting the collocation tests scores. Data was collected using, Gyllstad's (2007) COLLEX and COLLMATCH tests, Webb et al.'s (2017) Form A of the updated Vocabulary Levels Test, Luk and Bialystok's (2013) Language and Social Background Questionnaire (LSBQ), and Moskovsky et al.'s (2016) L2 Motivational Self-System Questionnaire (L2MSS). Participants (N = 136) from a Saudi university completed the questionnaires. The results indicated that although there were positive relationships between the collocation scores and the three independent variables, only vocabulary level and informal language exposure were significantly correlated. Finally, the multiple regression analysis showed that vocabulary level and informal exposure were significant predictors of the learners' collocational knowledge. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]