Young girls like Tara Mounsey have long been taking hockey stick in hand to challenge their brothers on frozen ponds. As they grew older, though, they were frozen out of the sport. Not anymore. This week Mounsey, 19 and a freshman at Brown University, will join 29 other women on the national hockey team preparing for the world championships next month in Canada. The U.S. team is already looking ahead to next February in Nagano, Japan, where, for the first time, women’s hockey will be an Olympic sport. ““This is all a dream come true for us,’’ says star forward Cammi Granato, who watched her brother Tony play for the U.S. Olympic team in Calgary in 1988.

For all these future Olympians, it’s a dream hard-earned. Mounsey started at the age of 5, playing pickup games outdoors. As she grew up she worried that, even at a solid 5 feet 7, 150 pounds, she might be body-checked out of the rink and ultimately the game. So she learned to skate circles around the boys, and her biggest challenge became finding a locker room in which to change. When Dorchester, Mass., native Stephanie O’Sullivan tried to play youth hockey at 5, the local league banned her. Her dad tucked her short blond hair under a helmet and signed her up as Stephen. By the end of the year she had revealed her true identity and broken the gender barrier. ““All of us are pioneers,’’ says O’Sullivan, 25, who, like Granato, has a brother in the National Hockey League.

Women’s hockey has passed quickly through the pioneering stage. In 1990, when the first world championship was played (the United States has been runner-up to Canada all three times), 5,000 female players were registered with USA Hockey, the sport’s national governing body. This season there are 22,000. Ben Smith, who coached Northeastern University’s men’s team before taking over the women’s squad last summer, says he has been dazzled by his players’ abilities. The differences between them and men, he adds, are ““all to the good. They’re much more receptive to coaching.''

The sole rule change from the men’s game bans body checking. ““There is no room for goons,’’ says Granato, who grew up in suburban Chicago. ““Everyone’s got to be skilled.’’ As a result, much as in women’s basketball, the game features more finesse and bears a strong resemblance to the men’s game of yesteryear. ““The fans are going to love it,’’ says O’Sullivan, noting the enthusiastic crowd when they beat a men’s team 2-0 before the recent International Hockey League all-star game. ““It’s pure hockey.’’ Just don’t ms. the net.