The spark of passion that inspires a person to write a nonfiction book is often very different from the reason someone else might buy and read it. This gulf sometimes sabotages the author's efforts to sell a nonfiction project, and bridging it can lead to publication and success.

One client came to us with a nonfiction project on the subject of healthcare. He was a highly credentialed, experienced, and articulate expert in his field with media exposure and a growing public platform. His manuscript eloquently outlined the current problems and a proposed solution, all in an engaging, entertaining manner. We helped him complete the proposal and found him an agent, but the first few acquisitions editors who saw it didn't come kicking down the agent's door for first crack at publishing it. We all had one of those forehead-slapping moments when the agent put her finger on the problem: while the ms gave a vivid picture of the overall subject, it didn't say much about what good the book could do for the individual reader. The solution was simple: the author added a couple of chapters giving readers advice on what they can do right now to improve the quality of the medical care. The proposal then quickly found a buyer and was published.

The benefit that readers hope to derive from a book is often termed its takeaway value. At first glance, it might seem that the takeaway value of much nonfiction is knowledge. But that statement is too general to be of much use-it has little takeaway value-because there are different kinds of knowledge with varying degrees of value to various audiences. The perceived takeaway value of How To Make a Million Dollars in Six Weeks on eBay would be very different on all three counts from that of Successful Merchandising Techniques in Han Dynasty China.

Historical nonfiction about the Civil War has perennial appeal in the USA. What's its takeaway value? For many people, they simply want to know more about this seminal period of our history; they may consider themselves Civil War buffs, have family connections to the period, or feel the issues are still alive today. With a well-written book about the Civil War that reveals new facts or interprets events in a new way, one might say that pure knowledge is sufficient takeaway value. But most people wouldn't buy the medical book I mentioned earlier for the sheer love of information about medical administration and insurance company operation; they'd also want to know how it related to them and what could they do to improve their own situation.

Knowledge can have a range of takeaway value. How-to books give very specific instructions on anything from finding a good mate to improving one's golf score. Other books may deal with practical subjects but offer more general advice rather than concrete, step-by-step how-to; self-help and home decorating books often fit into this category. Exposés, especially of celebrity lifestyles, offer knowledge to fuel conversation, gossip, self-congratulation, and schadenfreude, which many people find very valuable. Inspirational books rhapsodizing about an approach to life or spirituality or God often have little concrete knowledge but instead seek to bring about emotional response and change in readers. Memoir and travelogue can make for entertaining and even enlightening stories. Humorous books make people laugh, which is good takeaway value.

Nonfiction authors often start with the premise that they know a book's worth of material about their life or field of expertise, they're passionate about it, and the knowledge warrants a permanent record. That's a fine reason to write a book. But then they need to ask another question: what's in it for someone else to read the book, someone who may not yet share the author's love of the subject? In other words, what takeaway value can the subject offer readers?

Often the trick is to figure out ways beyond the obvious to add takeaway value. Richard Preston's The Hot Zone contains much knowledge about the origin and spread of infectious diseases and offers information to help readers protect themselves, but that's not what made it a hit. It became a bestseller because he wrote it as a gripping nonfiction thriller rather than as a more conventional nonfiction book arranged by subject matter. To the takeaway value of knowledge, he added the takeaway value of thrills and entertainment.

For example, perhaps you're thinking of writing a memoir about your travels, which had a profound effect upon you-that's your reason for writing it. But now try to figure out why someone else might want to read about your travels-what's the takeaway value? Well, there's the inspirational value you started with. But is that enough to attract an agent, a publisher, and a viable number of book buyers? What takeaway value could you add? Maybe it should read more as a travelogue than a personal odyssey, and so add knowledge of the world. Paul Theroux's travel books add a curmudgeonly voice that in itself is entertaining and keeps the narrative real. J. Maarten Troost's The Sex Lives of Cannibals adds enough humor to make this intimate travel memoir flourish on laughs alone. A thoroughly researched appendix might add the takeaway value of a guidebook.

One of the oldest pieces of advice for writers is to put yourself in your readers' shoes, and it's particularly pertinent to finding and enhancing the takeaway value of your nonfiction project.