Although few New York City teenagers have bosses to check in with or clients to tend to, a growing number of them are keeping track of their schedules, contacts, and e-mails on Internet-enabled electronic organizers, or “smart phones,” such as the BlackBerry Pearl and Palm Treo.

The state Supreme Court recently upheld a citywide ban on bringing cell phones to public schools, ruling against a group of parents claiming that access to cell phones is a matter of student safety. The city confiscated more than 12,000 such phones from public school students last year. But it’s a different story at city private preparatory schools, where cell phones and, increasingly, smart phones are commonplace — and need not be concealed.

With his new BlackBerry, a junior at the Dalton School on the Upper East Side, Matthew Ressler, said he plans to keep track of his homework assignments, exam dates, basketball practices, and volunteer activities. “I think it will keep me better organized, and I won’t have as many missed appointments,” Matthew, 17, said of the device, a recent birthday gift from his mother. “It’s really like you’re organizing a professional career.”

Matthew said that in recent months, many of his Dalton classmates have replaced their paper calendars with so-called personal digital assistants, or PDAs. Students are not supposed to use such devices in class, he said, but many teachers don’t enforce that rule. “You say, ‘This is my planner,’ and they say, ‘That’s fine,'” he said.

Students and faculty at the Trinity School on the Upper West Side can upload an academic calendar specially formatted for PDAs from the “Trinity Information Network,” a sophomore at the Upper West Side school, Gil Newman, said.

Gil received a hand-me-down Palm Treo six months ago, when his father upgraded his smart phone. Since then, the 16-year-old has been using the PDA to stay on top of his homework assignments, appointments, and extracurricular activities. “I’m definitely more organized,” he said, reaching into his pocket and pulling out his camera- and multimedia player-equipped Treo.

Even more than the calendar and camera features, teenagers say the main draw of the BlackBerry, Treo, or T-Mobile Sidekick is the instant messaging and Web capabilities — allowing them to update their profiles on social networking sites such as Facebook and MySpace or to fire off e-mails and text messages between (and sometimes during) classes.

The launch earlier this year of the BlackBerry Pearl, which is thinner, lighter, and comes in more colors than other BlackBerry models, as well as Palm’s new expanded color palette for the Treo, signals that the manufacturers are looking to expand their customer base, an editor at the technology magazine CNET.com, Bonnie Chaa, said. “BlackBerry and Palm have looked beyond business users, so I’m sure reaching teens is in the back of their mind,” she said.

One 17-year-old Dalton student who has owned a BlackBerry for about a year, said many of his classmates are anxiously awaiting the launch of the Apple iPhone, which, he said, “would do everything a BlackBerry can do, but it’s sexy.”

For now, the Sidekick-3 and the BlackBerry Pearl are popular with younger consumers, a cell phone and smart phone sales representative at Ameritel on the Upper East Side, Igor Groysman, said. About 30% of the store’s total PDA sales are to buyers under 18 — and some are as young as 9, he said.

The Sidekick-3 and BlackBerry Pearl retail for about $400, but costs can vary widely depending on the retailer, the wireless provider, and the service contract.

At Columbia Preparatory School on the Upper West Side, sophomore Jillian Roffer, 15, estimated that one-third of the students carry PDAs. Jillian recently traded in her old cell phone for a BlackBerry Pearl. She said she uses it primarily to chat with friends on BlackBerry Messenger — a free instant messaging program for BlackBerry users — and keep track of softball games and friends’ birthdays.

Another student at Columbia Prep, Wade Yacker, 17, said he doesn’t use most of the features on his BlackBerry Pearl. “For me, having one is completely pointless,” he said. “I could use a cell phone. This is just a little more stylish.”