This research attempted to study how using an advance organizer model can influence meaningful learning of new concepts for ESL learners in collaborative classrooms. The objectives were 1) to study the effects of using the advance organizer model, and 2) to study the student achievement after using the advance organizer model to compare to the 80 percent criterion. The study sample is purposively limited to 20 students in a class of the Introduction to Skills for Leadership and Management at Mahidol University International Demonstration School, Thailand. Post-test and observation forms were used as research tools. The data were analyzed by content analysis, mean and standard deviation. The findings revealed that 1) The effects occurred in both instructional and nurturant effects. The students engaged effectively in learning and acquiring information. Students discussed and exchanged information using existing knowledge and experiences to connect and explain the ideas to others. The instructional design also meets the steps of the advance organizer model. The teacher designed the tasks of learning follows the three phases of the advance organizer format. 2) The student achievement after using the model to meet the criteria of 80. This study reflects that the model can influence meaningful learning of new concepts and improve academic achievements for ESL learners in collaborative classrooms. However, few researchers have addressed the problem of collaborative learning in large courses. Hence, further study should focus on implementing the model with higher numbers of students to confirm its effectiveness.