Project-based learning is an essential part of a software engineer's education. The learning achieved through projects can be improved through structured interaction between more experienced students and those students encountering their first software engineering project. In this paper, we report on our experience over three years with trials of several forms of interaction between undergraduate students at the third- and fourth-year levels. This mentoring involved full year project subjects at both year levels. We discuss the problems encountered during these trials, and describe how the interaction was varied in response. We examine the benefits achieved through this interaction and provide details of student feedback. Such benefits include broadening the experience of the fourth-year students, providing a form of mentoring for less experienced students, and improving both the project process and the quality of the project product.