It all started eight years ago, when Julia Field was driving to a meeting and instead drove into the car ahead of her. ‘‘I wasn’t paying attention, and I rear-ended someone,” she says, still a little abashed. Field, an artist/activist with a wide-ranging résumé (she was, among other things, art director of Seattle Weekly, art director and managing editor of KidStar magazine, and a cofounder of Reflex), was spooked. “I had a 1987 Honda Accord with 100,000 miles on it,” she says, with perhaps just a whiff of nostalgia. “I thought I’d drive it another 100,000.” But now she also had an abiding fear of crashing again. “First I decided not to repair it. Then I decided not to replace it.”

Going carless was terrifying: “I thought, ‘Omigod, my life as I know it is over, I won’t be able to do the things I like to do and need to do.’ ” Then she realized she could clamp a basket on her bike and carry what she needed from the store. Riding the bus was easier than she expected. But it wouldn’t get her to the volunteer work she was doing at the time, at the state prison in Monroe. Again, necessity bred a solution: She caught rides with coworkers and even stayed at the home of one, affording a chance to talk outside the pressure cooker.

The change did entail some sacrifices, or at least lifestyle changes. “I’ve probably taken fewer trips to the mountains than before,” Field says. But she could rent a car for the weekend when she wanted and still come out way ahead of the cost of auto ownership — let alone the risk of another accident. Overall, she was surprised how quickly she adapted to being car-free. “I got very quickly from the point of not having a car to never wanting one again.”

In 2006 Field got involved in her neighborhood’s eco-community-building effort, Sustainable Ballard, (“a blueprint for EveryTown, USA”). Being a starter-upper sort, she cast about for a ways to make her town and EveryTown more, well, sustainable. Clearly, driving was the elephant in the road: “Of all the possible household behavior changes, it’s the one that can make the most difference.” Transportation accounts for nearly 60 percent of CO₂ emissions statewide and 70 percent of the Puget Sound region’s air pollution.

Eco-scrooges might grumble that we’re already doing our bit out here by getting most of our electricity from dams, which don’t pollute the air; people elsewhere in the country emit just as much by driving and far more by heating, cooling, and lighting their buildings with oil and coal-fired power. But our dams do strangle fish runs, and roadway run-off laced with oil drippings and brake-lining dust poisons the waters. So driving less is one way to make up for the damage done by hydropower.

The problem is that guilt, shame, and good intentions only go so far in changing behavior. We’ve all heard, or had ample opportunity to hear, about the automobile’s baleful effects, and almost all manage to blithely ignore them or rationalize our own driving. (I once spoke to a hyperdriver who commuted more than 40,000 miles a year, driving solo, but proudly declared that she was doing her bit by driving a compact Kia.) And most people don’t get anywhere with vague resolutions like “losing weight” or “driving less.” You need to resolve to lose X pounds in Y weeks, and so on.

What was needed, Field realized, was positive reinforcement for concrete commitments – and above all, positive spin. Then one morning she woke up with a word in her head: Undriving. Instead of “not driving,” you could take an affirmative step, and have some fun with it. If you would commit to one petrol-reducing measure, from selling the car to taking the bus to work once a week, she would make you a wallet-ready Undriver License, complete with the kind of picture you wish the DMV would allow, and a check-off list to remind you of the pledge you’d made and other steps you could take.

It was just the thing for our recognition-craving age, when all the children win ribbons and grow up to collect “friends” and “likes” on Facebook. And a great conversation piece. Field flashes hers when she’s asked for ID.

She debuted Undriving at the 2007 Sustainable Ballard Festival and had a hit; 437 newly licensed undrivers walked away that weekend. Since then, she and her fellow undriving instructors have recruited more undrivers at fairs, conferences, and schools in Seattle, Redmond, Portland, Spokane, and Olympia, and at commute-trip-reducing workplaces such as Children’s Hospital and the Gates Foundation.

A collaborator at Olympia's Intercity Transit came up with the “brilliant idea” of taking the license-making station to middle school dances, where kids can pose with friends for license photos, then each get a copy and hold each other to their pledges. (“I will nag my mother until she stops driving two blocks to the store.”) And so they reach a cherished rite of passage early — with a difference. It may be the only driver's license some will ever get; in the United States and other rich countries, a large and growing share of young people are forgoing driving altogether and getting around digitally instead. Naturally, Undriving recruits via website and YouTube channel, with testimonials from satisfied undrivers.

So far more than 8,500 undrivers have enrolled. Field and company survey them later by email; she says “20 to 40 percent” respond, a remarkable rate. Of those, “72 percent establish new transportation habits, and 86 percent say they show their licenses to other people.”

Those new habits vary widely. Many new undrivers pledge to walk or take the bus. For one, who would automatically get in his car every time he left house, it was the simple step of taking his car key off his key ring, so each time he prepared to leave he would have to stop and think, “Do I need the car or not?

One fairweather bike commuter pledged to get good rain gear. Another pledged to fix his wife’s bike. And another, who’d already raised a family without a car, vowed to find an adult who didn’t know how to ride a bike and teach ’em.

Results like that have won Undriving plaudits in unexpected places. The Spanish edition of Marie Claire hailed el carné de des-conducir. The New York Times’ Wheels blog saluted Undriving as a remedy for the “daily psychological and physical torment” that some (but not all!) drivers endure — without mentioning that it might also have some broader benefits for planet and community. (That might put off Wheels’s automotive advertisers.) And earlier this year Field received the national Alliance for Biking and Walking’s Susie Stephens Joyful Enthusiasm Award, named after a redoubtable Seattle-based advocate for bicycling and urban forests who — in a grimly ironic turn — was killed by a tour bus in a crosswalk in St. Louis, where she was training national parks staff in bike-friendly planning.

It was a particularly gratifying honor; Field had already planted two street trees in Susie Stephens’ honor. But she now faces the dilemmas that stymie many startups, commercial as well as nonprofit: How long can she continue to run it as a semi-volunteer operation? (So far she and her volunteers have kept it going with paid "station appearances," donations from undrivers, and a few grants, “but we haven’t had time to apply for a lot of them.” She’d like to hire a paid manager; it's a fulltime gig for her.) And, can it scale up to achieve its potential impact and become securely self-sustaining?