This series consists of McLean's university notebooks and some essays; there is a very small extent of pre-university school work. The notebooks reflect the courses which McLean took, first at the University of Victoria (his father was a minister in Victoria). All the notebooks from 1958 on (the vast majority) are from McLean's student days at Knox College, University of Toronto. In addition to the notes and essays there are also some clippings and print material, as well as reports, on religious issues dating back to the 1930s.
There is a small run of theology notes from McLean's father, Rev J. W. L. McLean, D.D.
There is in this series a large run of material reflecting McLean's work as pastor of Knox Presbyterian Church in Waterloo in the late 1960s and 1970s: his work with the Church administration, with Church committees (such as the church's Centennial Committee), his presbytery reports to the flock, his pastoral work in visiting the ill in hospital (and the reports he compiled regarding such visits).
There is a large run of reference material, much of it print and near-print, although there are notes of other commentators as well as their writings, which McLean amassed to serve as a resource in composing his sermons. The material is arranged by subject and theme. It reflects something of the 1960s era, and how that era altered the formerly more staid and orthodox mentality of churchmen of earlier generations.
Finally, there is a small run of files dealing with the Presbyterian Church in Canada, especially the International Affairs Committee of the Church, which details McLean's role in it, and his contribution to making it a forward organization, very much interested in improving the lives of humans in this world, and solving issues of poverty, human rights abuse, Apartheid and the like in Africa, China and elsewhere.
In sum, this series is a very rich component of the overall McLean fonds. It shows the inspiration behind McLean's decision to become a minister, and the educational process of studying for the calling; it demonstrates how the calling of minister changed following the dramatic 1960s; it accounts for the social and political dynamism of modern churches.