Learning Arabic as a second language (ASL) in Arabic-speaking countries is yet to be investigated thoroughly. The present study examines 61 ASL learners from 25 countries in seven Saudi universities using a quantitative and qualitative questionnaire, with Ajzen's theory of planned behaviour used as a theoretical framework to elicit and analyze the participants' intentions, attitudes, motivations, and challenges. The findings of the quantitative items show that learners hold significant and positive intentions, attitudes, and subjective-norm and perceived-behavioural-control beliefs regarding learning Arabic. These findings show the usefulness of using social psychology to elicit and understand ASL learners' beliefs and predict their intentions to learn Arabic by adapting valid and published questionnaire items. The qualitative results show that religious factors are what motivate ASL learning in Saudi universities. For example, Arabic is the language of sacred texts, the language of the Prophet Muhammad, and the language of Heaven. The most-reported challenges are the instructors' use of local dialects and inadequate training in teaching ASL. When designing curricula, policymakers should consider social factors such as religion, literature, history, and students' backgrounds. It is also recommended that language researchers use theories from other related disciplines to understand fully the perspectives of ASL learners.