Jill Kirby, the mother of five children who all play sports, sits with her daughter Allie Kirby, 11, as they watch a youth baseball game June 10 in Buffalo Grove, Ill. Earlier in the month, park district officials in the Chicago suburb posted signs asking parents to behave and keep the games in perspective. But Kirby wonders if they'll really do any good.

BUFFALO GROVE, Ill. — No parent here has rushed onto a playing field to jump a referee who made an unpopular call. No adult has gotten angry and slugged or pushed a coach or a young player, as has happened elsewhere. Nor have there been any of those embarrassing sideline brawls you sometimes see posted on online video sites.

At least nobody’s admitting to it.

Still, parent behavior in this quiet suburb north of Chicago has been questionable enough to cause the park district officials to post new signs at ball fields with what you might call a few gentle reminders.

“This is a game being played by children,” the signs in the Buffalo Grove Park District begin, with the words “game” and “children” highlighted in bold letters. “If they win or lose every game of the season, it will not impact what college they attend or their future potential income.”

The campaign, which began this month, is relatively low-key. You might not even notice the small blue signs if you weren’t standing right by them. But they speak to a growing movement in youth sports — aimed at reining in parents who, many say, are too involved, too competitive and in need of a little perspective.

“I just want to get back to what I was brought up with as a child — and that’s, ‘Let the kids play,”’ says Dan Schimmel, the park district’s executive director.

Elsewhere, some youth sports leagues are requiring parents to sign codes of conduct or recite pledges before games, promising in front of their children that they’ll behave. If they slip up, they might be pulled aside for a conversation or kicked out of a game if a warning does no good.

Other leagues occasionally have “silent” games, where parents and sometimes even coaches can only offer encouragement or cheer and clap, but can’t direct the young players or say or shout anything too negative.

This, say coaches, leagues and even some parents and kids, is about parent behavior that increasingly goes way over the line and interferes with a child’s ability to enjoy something that’s supposed to be fun.

“We’ve all seen that person on the sidelines and we’re thinking, ‘Are they really going there? Really?”’ says Brian Sanders, president of i9 Sports Corp., a national franchiser of youth leagues and camps based in Florida that uses sportsmanship as one of its cornerstones.

In some cases, violent behavior has led to criminal charges — in Newark, N.J., for instance, where parents allegedly beat up a Little League baseball umpire because he wouldn’t call a game because of darkness.

“The level of competition in youth sports has gotten exponentially greater, forcing this level of hypercompetition,” Sanders says.

Haley Small, a 19-year-old college student who played soccer and then traveling softball through high school, puts it this way: “The more competitively I played, the more interesting the parents got.”

“We’d joke about it, but it’s serious. Some of my friends were walking on eggshells,” says Small, now a student at Ithaca College in New York. “We hear a lot more than people think.”

It gets so bad sometimes that some players wish their parents would just stay home, she says.

Laura Marinelli, who coaches Small’s younger sister on a traveling softball team for 12- to 14-year-old girls in Essex County, N.J., also has noticed more over-the-top parent behavior in recent years.

Marinelli recalls one dad who was angry about a play on the field and tried to tackle her assistant coach during a game. The coach was able to duck the parent and ended up throwing him to the ground.

At a national tournament last year, she says a father of a player was so unhappy with a decision she’d made that he ran at her in the dugout, screaming and pointing in her face, causing some of her players to cry. Ultimately, she asked his daughter to leave the team because she felt the dad had repeatedly violated the team’s code of conduct.

“The girl is a phenomenal softball player. She’s a sweetheart — and a great kid,” Marinelli says. “But I can’t have a parent like that on the sidelines.”

Kicking kids off teams is one of the more serious punishments that leagues and coaches use to try to keep parents under control. Some leagues and tournament officials also are giving umpires more power to warn offending parents and coaches and then ask them to leave if they ignore the warning.

Some teams also assign parents to be “culture keepers,” asking those people to help keep the yelling and negativity from fellow parents to a minimum.