The purposes of this study were 1) to examine the effects of the Communicative Approach (CA) on learning and motivation to learn in a class of 40 students, 2) to investigate the effects of Team Teaching (TT) by a Japanese teacher and an assistant English teacher (AET) on learning and motivation to learn, 3) to clarify the learning process of CA and TT, and 4) to investigate the relationship between learners' affective factors and the two teaching methods (CA, GA), that is, Aptitude Treatment Interaction (ATI) effects. A 2×2 factorial design was adopted: two teaching methods, i. e. Communicative Approach (CA), Grammatical Approach (GA) in two teacher's conditions: a Japanese teacher with an assistant English teacher, a Japanese teacher only. One hundred and fifty-eight sixth graders were assigned to one of the four conditions and were taught English for a period of eight day. The results indicated that the Communicative Approach produced higher oral results, and that CA tended to motivate learners towards communicative activities. ATI effects were observed between the attitudes towards English and the two teaching methods when motivation would be used as a dependent variable.