The four-day workweek is hardly a new idea, but as Niraj Chokshi wrote recently in The New York Times, the dream of shortening the workweek has mostly failed to become a reality.

That's why it's worth paying attention to how one company's experiment with the concept has been so successful that the firm has made the practice permanent. And the benefits have been both measurable and impressive: higher productivity. Better morale. Increased profits.

If you're curious about the idea, you should read The 4 Day Week by Andrew Barnes, founder of Perpetual Guardian, New Zealand's largest corporate trustee corporation. In the book, Barnes not only makes a case for why the four-day workweek is such a good idea, he also explains how to do it.

Here are nine steps Barnes recommends you take if you're considering a four-day workweek:

  1. Start by articulating your purpose. "The four-day week is only one form of flexible working, and it may not be right for every company," writes Barnes. "Be clear about what you want to achieve ... if your objectives are explicit at the start, success can be measured accurately."
  2. Engage experts from outside the company. Perpetual Guardian worked with academic researchers who were able to design a structured pilot test and measure key factors like engagement and productivity.
  3. Gather data about key metrics before you begin. Barnes writes that his firm "erred in announcing the trial before amassing a comprehensive set of pre-trial levels of engagement and work-life balance in the company. An early data set would have served as a control against the inevitable surge in engagement scores when the trial was announced."
  4. Run a pilot/trial. Doing so "allows you to gather data to compare your business to others of similar size in other markets and industries. And by testing the model throughout the company, you can find out whether greater efficiency would come as a result of staff improved focus and motivation." Perpetual Guardian originally planned to do a six-week trial, but quickly decided that an eight-week pilot would work best.
  5. Don't over-engineer the plan. At Barnes's company, the premise was simple: a 100-80-100 rule in which employees received 100 percent of their pay for working 80 percent of their time but delivering 100 percent of agreed-upon productivity. Employees were "only required to work for four days provided that they meet productivity targets agreed on with their managers." 
  6. Consult your lawyers. Perpetual Guardian sought legal advice before the pilot and again when implementing the long-term version of the program. This was especially important because of New Zealand's labor laws. "Because what we were proposing had never been done inside the New Zealand legislative framework, we had to be sure we could offer a four-day week, even temporarily, and stay within the law."
  7. Once the basics are in place, ask employees for their input about how to design a trial "in accordance with their individual and team workloads, performance objectives, and personal schedule preferences."
  8. Expect surprises--and bumps--along the way. Although Perpetual Guardian got mostly positive results during the four-day workweek trial, issues did arise. For example, some teams experienced stress because of deadlines and other pressures. Other teams worked compressed working hours (10 hours a day over four days) instead of the intended working hours. And some leaders were not entirely supportive of the effort.
  9. Keep soliciting employee feedback. People have good ideas and valuable insights, so make sure there are lots of ways to discuss obstacles and offer suggestions.

Is the four-day workweek for every organization? Definitely not--there are still many challenges--but Barnes's book is an interesting exploration of this interesting concept and a road map of how his firm made the four-day week work.