In the U.S., union membership has fallen significantly in the last 50 years. According to data from the Bureau of Labor Statistics, the union-membership rate was 11 percent in 2015—roughly half of the proportion of Americans who belonged to a union in 1983.

One of the ways unions organize workers is by salting—when a union organizer gets a job at a company with the intent of organizing workers from within. Salting is legal, but employers tend to not be too fond of people who do it.

James Walsh became a salt after college with the intent to tell a first-person story about his experiences. He spent two years as an undercover labor organizer for Unite Here, a large union that revived salting in an effort to increase membership; he salted at two casinos in Florida, a state where private-sector union membership is a measly 5.7 percent. I recently spoke with Walsh about his new book, Playing Against the House: The Dramatic World of an Undercover Union Organizer, and why he believes that union membership remains important in the 21st century. A lightly edited transcript of our conversation follows.

Bourree Lam: Where did the idea come from, and why did you decide to become involved in salting?

James Walsh: I first heard about salting while in college. A few friends—the most radical, politically active students on campus—salted hotels after graduation. I was dumbstruck by their dedication. Some of them had graduated with honors, now they were working as bellmen and room-service attendants alongside folks who would have killed for the opportunity to earn a college degree.

Salting intrigued me as a story, but it wasn’t something that I wanted to do. That is, until a job interview with a popular historian to be his research assistant, who encouraged me to salt and then write about my experience. At first, I was skeptical. But after a day or two of thinking about it, I decided it would be a really good way to investigate why low-wage service-industry workers weren’t joining unions, a fact that is hard to understand given that, by just about every metric, unionized workers have a better quality of life than non-union workers. So, I reached out to some union folks (who didn’t know that I wanted to write about my experience) and told them I wanted to salt. They sent me to Miami.

Lam: You mention in the book that recruiting salts is hard. Why, in your opinion, are Sarah, the Unite Here organizer you worked with, and the other salts you met in Florida motivated to do it?

Walsh: Everyone I talked to who had been part of a successful unionization campaign (salt, organizer, worker) talked about the high they felt once they’d won. I think Sarah, and the other salts, had witnessed the value of salting in successful campaigns and were eager to grow the program. By nature, salting is counter-intuitive—someone who believes in the value of unions gets a job at a non-union shop. Add to that the fact that many of the salts I met were young activists with college degrees, and it’s easy to understand why Sarah and many other salts felt as if they were a part of a counter-culture community that they were eager to expand.

Lam: Take me through the basics of how salting works and how you organized workers at the two Florida casinos, Calder and Mardi Gras.

Walsh: The most important part of any union campaign is building a leadership committee at work comprised of people who have sway among their friends and co-workers and who are strong enough to stand up to managers. I thought identifying leaders in the workplace would be a lot easier than it actually was. At first, I was drawn to funny or popular people, but I would eventually realize they didn’t have fight or weren’t mature enough to take on management.

I worked hard to get to know my coworkers. I tried to hang out with them outside of work as much as possible. I went to the batting cages, bowling, church, a new-age Buddhist service. I learned to cook Haitian food and did a training session with an amateur boxer. He spent the entire time encouraging me while chuckling at how weak I was.

Eventually, I found leaders like Kalia. Kalia’s father was a drug dealer who was killed when she was a kid, and her mother was a drug addict. Kalia grew up taking care of her younger brother. My coworkers listened when she talked. When a surly manager gave her a hard time after one shift, she called him out on it. He told her to come to the office so they could talk about it and Kalia said something like “Nope, we’re having this conversation right here where everyone is listening.” The manager walked away and never bothered her again. I knew we had our first leader.

Lam: Was getting caught or being noticed by managers the number-one thing to avoid?

Walsh: I never worried about getting caught. Once inside, I rarely talked about the union and salting. No matter how well-trained managers are to recognize salts (which they are!), they have no way of knowing. The best way to avoid being found out was to do my job—I was a buffet server at Calder and a bartender at Mardi Gras—well.

Lam: In your account, it seems there was a lot of pressure on you from Unite Here to stay on their timeline. Why was that?

Walsh: The local chapter in Miami had a plan based on contracts the union had signed with the casinos. The contracts essentially said the union would help legalize slot machines in South Florida, if the casinos in turn agreed to remain neutral during our union campaign. (They didn’t.) Those contracts were set to expire so we had a real deadline.

Lam: There’s a lot of dialogue in your book. Did you record the conversations?

Walsh: Nope. In Florida, you need people’s consent in order to record conversations. So I have tons and tons of pocket-sized notebooks, quotes written on receipt paper, and emails I sent to myself in the bathroom. I brought a tape recorder to work only once. I thought I was going to be fired that day and I wanted to get everything exactly right, Florida laws be damned.

When a manager came over and said they wanted to see me in human resources, I put my hand in my pocket and hit record. I must have hit the wrong button because I didn’t record anything. The National Labor Relations Board recently ruled that employees can record work-related conversations. I think it’s still unclear how that ruling affects local laws.

Lam: Did you have doubts about going ahead with the book after your experience salting, or after telling your union colleagues at Unite Here about it? What were their concerns? Are you concerned that it’s going to damage the work of salts and the labor movement?

Walsh: I knew coming clean about the book would be extremely hard, and so I waited until I had a book deal and had written quite a bit, so there was no turning back.

The union was most concerned about the book tipping their hand, which I understand. However, anyone who thinks the huge corporations that run the workplaces service unions are trying to organize don’t already know about salting isn’t giving them enough credit. Many big companies know about salting and train management to recognize salts.

Furthermore, the Supreme Court ruled that salting is perfectly legal. The union is in a tough position because the companies (and people) interested in dealing organized labor its death blow have plenty of resources, and a challenge to any Supreme Court ruling isn’t out of the question. I understand the need to hide salts from campaign to campaign, but not the desire to hide it from the general public.

Lam: Why not?

Walsh: The value of salting is in the chance to have candid conversations with co-workers without the pretense of a union house visit. That value is based on the secrecy of individual campaigns, not the program’s secrecy. In fact, shrouding the program in secrecy makes it seem nefarious or manipulative, which it isn’t. Furthermore, people want to hear these stories! People should hear these stories! It’s hard to tell the story of a disappearing middle class—and the reasons so many workers aren’t joining unions—in a compelling, personal way. I hope this book does that.