As soccer picks up fans and followers in the U.S., entrepreneurs are betting that they’ll be able to make a lot of money off of a sport that’s already enormously popular elsewhere. Will their bets pay off?

There are several ways to measure the popularity of a sport. It could be judged by how many eyes are watching televised games or how many advertising dollars it draws; how many people play the sport or the prevalence of little-league community organizations and impassioned fans; or some combination of all of the above. And then, like the music industry’s shift to merchandise, there’s how much gear it sells.

In 2007, $103 million worth of soccer balls were sold wholesale in the United States, along with $179 million in soccer-related accessories. Just six years later, in 2013, the market moved $123 million of balls and $213 million of accessories—an increase of around 20 percent.

As equipment sales demonstrate, soccer’s prominence has slowly been growing in the U.S. since at least 1994, the first (and only) time the FIFA World Cup was held in this country. And with attention mounting around the upcoming 2014 World Cup in Brazil, U.S. soccer may be hitting an economic tipping point, with big-money deals for teams and TV distribution. Tastemakers and entrepreneurs are betting on the growth of a massively popular industry. In other words, soccer balls are only the beginning. But how much of a gamble are businesses making that U.S. soccer will gain a football-size following?

Soccer has a good conversion rate—it turns participants into consumers and evangelists who spread the sport and the brand further.

Though the U.S. fielded men’s teams for the World Cup in 1930 (they finished third), 1934, and 1950, it went on hiatus until 1990, participating in every Cup since. Major League Soccer, the U.S. national soccer organization, has a much shorter history. The league was founded in 1995, following the surprise hit of the 1994 Cup (which drew 3.6 million attendees and 11 million domestic TV viewers at its height), and featured 10 teams competing in the first national championship in 1996. MLS now has 21 franchises, and they’re gaining their own sizable audiences.

Soccer (in the form of U.S. Major League Soccer) has caught up to Major League Baseball among young sports aficionados—both sports have captured 18 percent of 12- to 17-year-olds as fans—according to the 2014 ESPN Sports Poll, which tracks interest in major league sports. The rise of soccer coincides with a surprising fall in the popularity of baseball, which had a 25 percent avid interest rate among that same audience just two years ago. (Football and basketball come in higher at 39 and 30 percent respectively, and hockey is the worst bet at just eight percent and falling.)

This positive interest in soccer doesn’t necessarily play out in other demographics, however. Only one-third of Americans said that they will follow this year’s World Cup competition (just seven percent said they would follow it “closely”), according to a recent Reuters poll. Eighty-six percent of Americans told Reuters they know “nothing” or “only a little bit” about the World Cup. The Washington Post found in another survey that just 28 percent of Americans identified as soccer fans; an equal rate predicted that they would watch the World Cup games.

What these surveys show is that while soccer has not yet hit the mainstream, it is certainly catching on. The Post poll found that respondents who had played youth soccer were much more likely to watch the World Cup and describe the sport as “exciting.” They were also more optimistic that the sport has a strong future in the U.S.; 62 percent of former players guessed the sport would become “more popular” in the next decade. To borrow a term from business, this suggests that soccer has a good conversion rate—it turns participants into consumers and evangelists who spread the sport and the brand further. And if more kids are interested in soccer now, as the ESPN poll suggests, then even more are likely to be in the future.

That young audience is a demographic that advertisers will pay to reach, as they already do in other broadcast sports. Ads during the 2014 Super Bowl broadcast cost an average of $4 million for 30 seconds—of course, networks also pay $39.6 billion for the rights to show the game and gain that mass audience. While viewership is much lower for soccer, the games are already being packaged and sold. ABC/ESPN paid $100 million to broadcast English-language FIFA events from 2007 to 2014, and Univision paid $325 million to broadcast in Spanish (Latin Americans are more likely to be soccer fans). Those numbers will likely rise in the future.

Sports teams themselves also become commodities, and U.S. soccer teams are no exception; they’re getting financial investment from some key players in already established sports industries. Robert Kraft is the “investor/operator” of the MLS team the New England Revolution. Kraft also happens to be the CEO and chairman of the New England Patriots, one of the most popular teams in football with a value of $1.8 billion as of last year, according to Forbes. Similarly, the owners of Manchester City, one of the major soccer teams in the English Premier League, are partnering with the New York Yankees to found the New York City Football Club, a new MLS team that will play its first season in 2015 at Yankee Stadium. With this lucrative cross-branding, investors must be hoping some of the Yankees’ magic will rub off on the new team.

Soccer is a passion, but the creation of new teams should be looked at in the same way as other new business launches. Should they attract reasonably large followings, they will be extremely profitable. In the European leagues, selling sponsorship of top teams’ equipment is already a $709 million industry. The Bayern Munich soccer team was valued at $896 million this year, with Real Madrid following at $768 million and Manchester United at $739 million. What entrepreneur in the U.S. wouldn’t want to see these numbers assigned to American teams?

Building the new soccer industry is all about developing strong brands and skillful teams with compelling narratives—and selling them to national sports fans (who are, in turn, sold to investors and advertisers). All in all, it seems like a better bet than putting money into soccer balls, though that might just pay off, too.