This thesis is intended to probe into how task types, topics and grouping affect the effectiveness of group work in the low-intermediate level college English class. It aims at providing teachers and researchers with deeper insights into the use of group work through an empirical study.The thesis consists of six chapters. The first chapter introduces objectives of college English teaching and learning and the significant role of group work in college English class. It points out the problems with the use of group work and shows the purpose, significance and scope of the present study. It also presents the organization of the thesis. Chapter two is concerned with the theoretical foundation of group work, and presents a critical review of previous studies on group work. Chapter three reports on the empirical study which aims to unfold what occurs during group work in a real college English classroom. In chapter four, the results of the empirical study are presented from the perspectives of language production, negotiation of meaning, modified output and peer assistance. Chapter five centers on an examination of group work used in EFL coursebooks. The author chose New College English II to evaluate the design of group work tasks and put forward suggestions for improvement. The roles of students and teachers in effective group work are also discussed. Chapter six concludes the thesis by summarizing the major findings of the study and proposing areas for further investigation.The study shows that task types, topics and grouping exert an impact on the effectiveness of group work in the low-intermediate level college English class. Required information exchange tasks have advantages over optional information exchange tasks in terms of language production, negotiation of meaning and balanced participation. Grouping has an impact on the success of group work. The selectively organized long-standing grouping seems to create a more cooperative environment for students than the randomly organized temporary grouping. The highly proficiency mixed grouping seems to benefit low proficiency students in terms of peer assistance. Topics play an important role in motivating students and as a result maximizing the success of group work. Taking into consideration all these findings, the author suggests that obligation to transfer information should be incorporated in the design of group work in EFL coursebooks, and topics and grouping should be taken as important factors in maximizing the success of group work.