So you are sitting down to write an index. You scroll to the first page in the PDF, or, if you’ve printed out the proofs, you place the first page on the desk in front of you, and then…what? What is your thought process? How do you decide what entries to extract? How do you read?

Reading to index is different than reading to edit, reading to learn, or reading for pleasure. I think of reading to index as a process of disassembly. I try to identify how the author has written and structured the text, and I then pull apart all of those pieces, big or small, and reassemble them into the form of an index. This is very much an active reading, in which I am identifying, analyzing, and making decisions. 

I generally look for two types of information when I draft an index.

• Specific details. These are names, places, companies, concepts, etc… that are explicitly mentioned and discussed. These are usually fairly obvious. If there are a lot of names or other such details, I may index a few pages, pick up these details, and then go back and re-read to make sure I also understand the larger discussion.
• Broader topics. These range from the metatopic—what the whole book is about—to supermain and regular discussions—both themes spanning the book and what specific chapters or sections are about. It is important to have index entries which correspond to these broader discussions, and so in addition to picking up specific details, I try to also understand the big picture. These broader topics are also tied to the structure of the index, as I consider how best to reflect the book’s structure in the index, and as I anticipate that these large discussions will become large arrays, anchoring the index. Depending on the book, as mentioned, I may need to read a section two or more times to properly mine all relevant entries. 

Once I have identified the large and small pieces that the book is made of, I need to decide how to translate that into the index. Here are a few tips I find helpful to keep in mind.

• Understand what you are reading. This may seem obvious, but I think it is worth stating. The temptation, at least for me, is to guess if I am unsure and to create an entry anyway. And sometimes guessing is the best I can do in that moment. I flag the entry for revisiting later and I move on. What can be more effective, though, is to read ahead a few pages until I do understand, and then go back and create the entry. It’s okay to be patient. Taking the time to understand can pay off later with better understanding of what comes next in the text and with less editing due to a stronger draft. 
• Place the information in context. Are you looking at a specific detail or a broader topic? How does the detail or topic relate to other details or topics? Can this be turned into a subheading? Should it be double-posted? Is a cross-reference necessary? What other entries does this suggest? While subheadings, cross-references, and double-posts can all be revisited later, when editing the index, I like to start thinking about them while writing the rough draft. The information in the book is an interconnected web, which the index should reflect. So as part of your thought process, get in the habit of looking for these connections. 
• Filter for relevance. In addition to understanding the larger context, also pay attention to relevance. Think about the audience before you begin writing the index. Consider how much space is available for the index. What should the index focus on? Sometimes I am not sure if an entry is relevant and so I pick it up anyway, labeling it for possible deletion later. But the more I can filter out now, the less I need to cut later. 
• Communicate with clarity. This is especially true for subheadings. Make sure that readers understand what this entry means. Be concrete and, where relevant, link back to the larger context. You don’t want to leave readers guessing, nor do you want to leave yourself guessing when you come around again to edit.

All combined, this is a lot to do while reading and indexing. It can be difficult to identify both specific details and larger discussions, while also weighing relevance, and paying attention to the context, and thinking about related entries, and thinking about how best to phrase for clarity. Reading to index is a skill that takes practice.

Remember too that the rough draft does not need to be perfect. My drafts are certainly not perfect, and while I am thinking about all of this while drafting, I spend about an equal amount of time editing. 

How you read is up to you. I tend to start reading and I type entries into Cindex, the indexing software that I use, as the entries come to mind. Other indexers prefer to first mark up the proofs, identifying what is indexable and making notes for themselves, before they go back and type up the entries. There is no right or wrong approach, so long as you are paying attention to all aspects of the text, both big and small.

If you are newer to indexing, you may find marking up the proofs to be a good way to visualize or make concrete this thought process. I marked up proofs the first 3-4 years that I indexed, which in hindsight was necessary for me to engrain this way of reading. Once indexing started to become habit, I stopped marking up, though I still read ahead sometimes to better understand what the text is about. 

Writing an index is a unique way to interact with the text. It does require a shift in how you read and see the text. Once you make that shift, indexing becomes easier.