Introduction. This paper contributes to the research on teacher burnout by distinguishing between two aspects of work demands that are usually merged in the “workload” construct: the quantity of the demands (quantitative demands) and the cognitive effort they require (cog-nitive demands). Such a distinction may offer insight into how educational administrators should manage certain types of work demands. Method. In an international sample of 209 kindergarten, primary and lower secondary teach-ers working in 110 schools from four different countries (Brazil, Chile, Ecuador, and Spain), we administered the Maslach Burnout Inventory (MBI) and the Copenhagen Psychosocial Questionnaire II (COPSOQII). We conducted three separate multiple regressions in which the work conditions (COPSOQII) were set (forced entry) as predictors of emotional exhaustion, depersonalization, and personal accomplishment (MBI). Results. We found that quantitative and cognitive demands predict teacher burnout different-ly: while quantitative demands predict emotional exhaustion and depersonalization, cognitive demands play a protective role in relation to those two components and also predict personal accomplishment. Additionally, we found that emotional demands positively predict emotional exhaustion and depersonalization, and negatively predict personal accomplishment. We also foud that support from colleagues and community positively predicts personal accomplish-ment, but shows no significant relationship with either emotional exhaustion or depersonaliza-tion. Discussion and Conclusion. Results suggest that the distinction between the quantity of de-mands and the cognitive effort they require is meaningful and important for future research and practice in the field of teaching. One important implication for educational administration is that the quantity of work assigned to teachers should be kept relatively low but, at the same time, this work should be cognitively activating and demanding.