For years, Ben & Jerry’s took steps to make sure that its ice cream did not contain artificial growth hormone. The company also has a self-imposed fee on its greenhouse gas emissions.

What Ben & Jerry’s did not have was a reliable way of ensuring that the dairy farms supplying it with milk were providing humane conditions for their workers, a major issue in an industry where many people work seven days a week for less than minimum wage.

On Tuesday, the ice cream maker, which is based in Vermont, took a big step toward changing that, signing an agreement with a farmworkers’ group that establishes labor standards for the company’s suppliers in the state, and creates an enforcement strategy that encourages workers to speak up about violations.

“We love to be part of innovation,” said Jostein Solheim, the company’s chief executive. “We believe in worker-led movements, and in bringing in dairy and doing it in Vermont.”