UPDATED 12/20/21
A developmental edit is probably best understood at the basic level by thinking about the word developmental. The manuscript begins to develop from its current state toward the final work you want it to be. In Scott Norton's book Developmental Editing: A Handbook for Freelancers, Authors, and Publishers, he personally defines developmental editing:
"...significant structuring or restructuring of a manuscript's discourse."
Norton discusses what I've already mentioned in my previous blog post on manuscript assessments, that even in the industry, opinions vary as to what significant means. At the University of California Press in Berkeley where he worked, a developmental edit was considered:
"...intervention that moves content from one chapter to another, or rearranges the lion's share of a chapter's contents within itself but that falls short of writing new material."
During a developmental edit, I make certain I have a firm grasp on two big-picture questions:
What is the purpose of the book? Don't lose sight of why this manuscript has been written.
Who is its intended audience? The author and the DE must keep at least one person in mind at all times who is the ideal reader.
My duties as a developmental editor can be wide-ranging, depending on the levels of experience and confidence of the author. But these are my primary responsibilities:
Suggesting a format that best communicates the thesis (message).
Restructuring the text to fit the chosen format, which can include adding or deleting material to make the text flow.
Ensuring consistent structure.
Identifying gaps in the material (in fiction, this can include plot gaps and problematic characterization).
Deleting text that does not achieve the agreed upon objective of the book or speak to the target audience.
Illustrations, diagrams, photos, and the like are taken into consideration during this phase, as well. If beta readers have been used, I will review their feedback and work with the author to decide how to incorporate suggestions into the material.
In addition to working as a nonfiction and creative nonfiction editor and writing coach, I am co-author, with Dr. Terri Lyon, of the book Make a Difference with Mental Health Activism: No activism degree required—use your unique skills to change the world. Visit my website page Make a Difference and Dr. Lyon’s activism website Life At The Intersection to learn more about Make a Difference, including how to place bulk orders.