Companies looking to increase revenue while boosting employee happiness should consider adopting a four-day workweek.

According to Business Insider, New Zealand nonprofit, 4 Day Week Global conducted a pilot program with companies in the US, UK, and Australia. The program was designed to determine what, if any, benefits there were from transitioning to a four-day workweek.

The pilot program’s results were rather enlightening, with company revenue increasing by 15%. What’s more, despite employee work intensity dropping, overall efficiency was up, as was employee satisfaction. In fact, one-third of employees said they were less likely to leave their job as a result of the change.

The study, conducted over an entire year, is one of the most comprehensive such studies, giving companies plenty of long-term data in support of a four-day work work.

“A concern we frequently hear is there’s no way the results from our six-month trials can be maintained, as the novelty eventually must wear off, but here we are a year later with benefits only continuing to grow,” said Dale Whelehan, CEO of 4 Day Week Global. “This is very promising for the sustainability of this model, and we look forward to tracking companies’ experiences well into the future.”

As Insider points out, at least one US lawmaker is using the study as impetus for permanent change in the American workforce.

“4 Day Week Global’s latest study make the urgent need for my Thirty-Two Hour Workweek Act overwhelmingly clear,” Rep. Mark Takano said in a statement. “The four-day workweek can be implemented with positive impacts on workers and businesses, and this extensive study bolsters the employee feedback from shorter trial studies. The four-day workweek is here to stay.”