Lesser pay for better work? US women's soccer stars say so.

In filing a wage discrimination complaint Wednesday, five stars of the United States women’s soccer team put into financial terms an argument that, so far, has been made chiefly by their feet: We’re better than the men.

The players’ complaint, filed with the US Equal Opportunity Employment Commission by Carli Lloyd, Hope Solo, and three others on behalf of the team, lays out the numbers in stark fashion. Despite generating $20 million more in revenue for the United States Soccer Federation (USSF) than the men’s team in 2015, the members of the women’s team were paid 38 to 72 percent less.

Outspoken goalkeeper Hope Solo put the claim in different, yet no less categorical terms. “We are the best in the world, have three World Cup championships, four Olympic championships, and the [men] get paid more to show up then we get paid to win major championships.”

Within the world of soccer, the lawsuit is merely the culmination of years of second-class treatment by both the USSF and FIFA, soccer’s global governing body, the women say. The men, for example, are barred from playing major international matches on artificial surfaces because of its adverse affect on the quality of the games and the potential for injuries. By contrast, women were forced to play the entire 2015 World Cup on artificial surfaces, despite protests.

More broadly, however, the lawsuit sheds a dramatic light on the persistent gender wage gap in America. A recent study, for example, has shown that as women become more prevalent in a field – even if they have equal levels of education, work experience, and skill – the pay in that field drops.

“It’s not that women are always picking lesser things in terms of skill and importance,” said Paula England, a sociology professor at New York University, and a co-author of the study. “It’s just that the employers are deciding to pay it less.”

For their part, the women of the US women’s soccer team argue that their skill and importance clearly outstrip that of the US men’s team. An estimated 23 million people watched the US women beat Japan in the World Cup final last July, making it the most-watched soccer game in US history. Before the tournament, the USSF was forecast to run a deficit in 2015; afterward, it turned a $17.7 million profit.

“This is one of the strongest cases of gender discrimination I have ever seen,” Jeffrey Kessler, the attorney representing the players, told USA Today. “This is pretty open and shut case.”

The discrepancies noted in the women’s claim range from World Cup bonuses to per diem expenses. For instance:

• If the US men win a friendly match (a game not associated with a tournament) against a Top 10-ranked team, each player gets a $17,625 bonus. If they lose, each gets $5,000. The US women get a $1,350 per-player bonus for a friendly win against any team, and nothing if they lose.
• If the US men qualify for the second round of the World Cup, the team gets a $4.5 million bonus. For the same achievement, the women get nothing.
• For per diem spending overseas, each member of the US men’s team gets $75. The women get $60.

In an appearance on the “Today” show, Ms. Solo added: “We continue to be told we should be grateful just to have the opportunity to play professional soccer, to get paid for doing it.”

To be sure, women’s professional soccer leagues have not yet proven nearly as popular or profitable as men’s soccer leagues, even in the US. The USSF partly underwrites the top US women’s professional league, the National Women’s Soccer League, because its two predecessors (the WPS and WUSA) failed financially.

Men’s “Major League Soccer brings in an average of 240,000 viewers at ESPN while women’s soccer ratings are barely a blip in comparison, averaging around 63,000 viewers (others put it closer to 100,000), but sinking at one point to just over 30,000,” D.C. McAllister wrote on The Federalist, a conservative news site, in July.

But the financial picture for the national teams is different. And that is the basis of the women’s claim. “The reality is that this team is more valuable to the USSF than the men’s team has been,” Mr. Kessler said in a conference call with reporters. “That’s what the facts show. And they would be justified in asking for more than the men are receiving. But the first step that they are seeking is equal treatment. That should be an easy step for the USSF to take.”