The present study compared the perspectives of 13 Assistant Language Teachers (ALTs) and 14 Japanese Language Teachers (JLTs) working together through the Japan Exchange and Teaching (JET) Program regarding the actual and potential impact of foreign instructors working in different school contexts. Particular focus was on analyzing responses to semi-structured interview protocols to determine views on ALT impact on school atmospheres, student learning and motivation as well as JLTs' pedagogical approaches, proficiency in English and extent to which they believe team-teaching to affect the difficulty level of their jobs. Participant narratives yielded three main themes, or findings. First, ALTs and JLTs differ in assessing the effects of team-teaching on solo-taught, or 'regular' English lessons. Second, ALTs are more likely than JLTs to sense improvement in team-teaching over time, while both groups perceive that the longer an ALT spends at a school, and the bigger the school, the less the impact of the ALT on school atmosphere. Third, and unexpectedly, ALTs and JLTs express different views as to whether or not team-teaching renders JLTs' jobs more difficult, with JLTs being much more positive on this point.