Diane Rosen’s workdays often begin at 8 a.m., and she fields on average between 25 and 40 e-mails a day. In any given week, she spends between six and 10 hours in meetings with officers, administrators, and divisional executive vice presidents, and her evenings are often occupied with events scheduled around her work. She’s not a corporate executive: She’s a private-school parent volunteer, specifically, president of the Parents’ Association at the Trinity School, a position that can require almost as many hours as a full-time job, but without the pay.

Active school volunteering is part of the unwritten social contract parents sign when they enroll their kids at an elite Manhattan private school. It can be both rewarding and a hotbed of political maneuvering. “Being P.A. president is a job that can infiltrate one’s life,” Ms. Rosen said, “because it’s a very visible position at school and it’s time-consuming. I field a lot of questions.”

For the schools, parent volunteers provide a huge unpaid labor pool of talented and bright workers who are dedicated to the school because of their children. Judy Blanton, director of the Episcopal School, said, “Parents do so much to enhance our program. There’s the Parent Help Committee, class representatives, the benefit committee, a lending library, and an art committee which helps select and mount the children’s artwork in our front hall.” George Davison, head of the Grace Church School, noted that about one-third of the parent body is actively involved as school volunteers, including many fathers. The activities include a book fair and street fair, as well as an annual auction.

One reason parents enjoy volunteering is that it makes them feel like an active part of their child’s education. Kari Jenson Gold, whose daughter attends the Nightingale-Bamford School, chaired the school’s book fair for two years and also chaired the father-daughter breakfast with her husband. She is a tour guide for prospective parents and works in the library once a week. She said, “I want my daughter to take education seriously, and to the extent that parents volunteer, it sends a message that it’s worth the parent’s time. Plus, it’s a way to give back to the school.” Ms. Rosen said, “You want to be where your kids spend time. Parent representatives in the lower school often work closely with the teachers.”

Some parents also reported that volunteering at schools had taught them new skills or helped maintain career skills. “That’s when I discovered e-mail,” Ms. Gold said. Julia Ryan, whose son attends the Saint David’s School, had worked for years in information technology. “Five years ago, at a Parents in Action meeting, I basically ‘outed’ myself as being technically savvy,” she said. The next thing she knew, she was creating a directory for the school on a database and is now listed as the “technology liaison.” The best part is that her volunteer gig has kept her current in her industry. “It’s helped me redefine what I want to do in the post-child years. I see parts of I.T. that I can do and the potential markets for consulting,” she said.

But it’s the social component of volunteering that draws many parents into the fray. Parents want to make friends and establish connections. “This is their children’s first school experience and chance to be part of a community in a big city,” Ms. Blanton said. “One of the selfish benefits,” Ms. Gold said, “is that I get to meet lots of people across grade levels and make friends.”

Then there are always those volunteer mothers who seem to live at the school. One mother whose daughter is at a private girls’ school calls these women “career volunteers.” She said, “Personally, I think it can take time away from being with your kids.” Another mother said, “It is a good portion of their social lives.” And for one frustrated Upper East Side mother, the volunteer meetings she attended were more like tea parties. “For many of these women, this is their social interaction of the day, and it’s not approached as a work-related activity,” she said.

Often these social opportunities breed a brand of social opportunists, particularly on the auction committees. “If you think that the kids are cliquey, try the moms!” said Victoria Goldman, author of “The Manhattan Guide to Private Schools,” now in its fifth edition. “These committees are clubby and self-selecting. It’s highly political. Move over Karl Rove.”

Serving on the auction committee, according to Ms. Goldman, “takes a little more than just raising your hand. You should know or be friends with someone on the committee and be able to offer more than just time, like being able to help secure a space, get great/expensive auction items, and solicit others – knowing the right people in the parent body well enough to ask them to bid on high-ticket items and donate.”

Many of these volunteers hope to become chummy with parents who can help them establish a foothold in the Manhattan social scene. Ms. Goldman said, “At certain schools, like Spence, Dalton, or Horace Mann, where the parent body are known to be movers and shakers, of course you want to get to know them, and this is a way. And you might rub elbows with Katie Couric or Uma Thurman.” One mother whose son attends a private boys’ school said, “I’m not interested in being a social climber, although I know many parents are. I also stay away from any political maneuvering that does go on.” Ms. Ryan said, “At pre-schools, things are probably crazier because you have a young child and you’re trying to get into country clubs and ongoing schools. Committees clique you in with other people who can do things for you or your kids.”

And some uber-volunteers are just plain power-hungry. Ms. Goldman said, “Volunteer work may seem thankless, but there is payoff. It’s prestigious. There is a place where your name is printed and it’s circulated among an elite population. For some volunteers, this is ‘It.'” Plus, according to Ms. Goldman, in many private schools the auction chair is the most powerful person in the P.A.

But for those parents who believe that being an active volunteer affords them special privileges, such as getting siblings into school, getting cozy with the college counselor, or asking for a particular teacher, one high-powered volunteer cautioned that this is a misguided notion. Said Ms. Rosen, “Parents need to recognize that it’s essentially a service job. You’re in service to the school. It’s pure volunteerism, and there’s not really power and glory.” Mr. Davison said, “Proximity does not mean access.”

The political jockeying starts with the often enigmatic process of choosing volunteer leaders. Ms. Blanton sends out forms in the spring asking parents on which committees they want to serve. Considerations include whether that person has served on the committee in the past and whether they have time to do the job. Some schools have nominating committees, and candidates are evaluated for such things as diplomacy and discretion. Naturally, the selection of certain parents over others can create tension.

Grace Church School has found a way to staunch the power struggling by choosing names out of a hat if too many people sign up for the same positions. “We make a big fuss that it’s done this way,” Mr. Davison said. “Some people complain about having to work with certain people, but overall, it makes for a happier parent body.” They have also doubled up on volunteer jobs. “They cover for each other, and this teamwork sends a positive message to the kids,” said Mr. Davison.

Whether it’s genuine volunteerism or careerism, most parents agreed that their volunteer experiences positively enriched their lives and those of their children. And when parents find themselves under a canopy of balloons, perusing the fabulous auction items they might win, they know that a team of people spent many hours creating a magical evening for all the parents, even if their motives were not purely altruistic. Parents also realize that it takes talent and top-notch organizational skills to make these events a success. Said Ms. Goldman, “These women can run a small country.”