Motivation can be conceptualized as a dynamic process which is a key contributor to mastering a second language. This study used the L2-Motivational Self System as the basis for a conceptual framework for studying the effects of external factors on learners' motivation. In particular, the role of teachers and parents was studied as the external facets of predicting learners' motivation. One hundred and twenty EFL teachers along with 1,270 of their students participated in the study. To measure motivation, the Persian version of Dörnyei's L2 Motivation Self-System Scale was utilized. Three key components of the scale, namely, criterion measure, attitudes to L2 learning, and instrumentality promotion were employed in measuring motivation. To assess the role of family in motivating learners, another subscale of Dörnyei's questionnaire, i.e., family influence was used. To gauge teacher burnout, the educator version of the Maslach burnout inventory (MBI-ES) was used. Structural equation modeling (SEM) was run to analyze the causal relationships among the variables. The results revealed that teacher burnout negatively influenced learners' criterion measure and their attitudes to learning English. However, the path leading from teacher burnout to instrumentality promotion was not significant. Furthermore, three direct, positive, and significant paths leading from family influence to learners' criterion measure, instrumentality promotion, and attitudes to learning English were detected. Finally, findings are discussed with reference to the context of Iran.