Few studies have investigated the impact of English language programs on second language (L2) students studying in Canadian universities (Cheng & Fox, 2008; Fox, 2005, 2009). This article reports on questionnaire responses of 641 L2 students studying in 36 English language programs in 26 Canadian universities. The researchers identified programs by their activity emphasis as either English as a second language (ESL) or English for academic purposes (EAP). Activity emphasizing speaking, social interaction, and general language development was viewed as ESL, whereas activity that emphasized academic reading, writing, and language development was considered EAP. The researchers used structural equation modeling procedures to examine the network of relationships between language program emphasis and participants' background characteristics in influencing academic and social engagement. A model of moderated mediation (Wu & Zumbo, 2008) was confirmed; that is, language program activities were found to account for variation in strategies which mediated academic and social engagement. However, the impact was moderated (lessened or strengthened) by three personal background factors: anxiety, stress, and motivation. This study refines our understanding of the positive impact of ESL and EAP programs on L2 university students' academic and social engagement.