Is it a proofread? Is it an edit? Is it both?!

After proofreading an academic textbook recently, some of which was quite complex, I was faced with one of the questions editors often have to ask themselves: Is this 'just' a proofread, or does it perhaps require some additional editorial intervention, even at this supposedly final stage of the publishing process? Where is the line between a proofreading exercise and an editing one? What I've learned over the past year or so as a newbie freelance editor is that there is sometimes no clear distinction, which can lead to much confusion for both client and editor! I've now done several training courses to broaden my editorial experience, one of which was in copy-editing and the other in developmental editing of non-fiction. Before doing this training, I naively thought my years of experience in creating and editing dictionaries content meant I was fairly well-equipped for the challenges of being a freelance editor and taking on a variety of different editing and proofreading work - so far, the verdict is that I have a solid basis to build on, in what is a very competitive and challenging freelance environment, but that it's very much a learning process. As the Germans would say: Man lernt nie aus.