These are not your run-of-the-mill potheads jammed into the long, narrow classroom at Oaksterdam University, a tiny campus with no sign to betray its location on busy San Vicente Boulevard south of the Beverly Center in Los Angeles. A serious vibe fills the loftlike space, where rows of desks are arranged like church pews under exposed ducts. No one clowns around or even smiles much. Instead, eyes fix intently on a screen at the front of the darkened room.

Projected there is a photograph of a healthy marijuana plant under an array of lights. Tonight's subject is Cannabis 101: growing the weed in indoor gardens. It's delicate alchemy, as most of these students, who range in age from their early 20s to late 50s, already know. During the 13-week semester, many tend and keep notes on their own clandestine nurseries in bedrooms and garages scattered around Los Angeles.

Encouraged by instructors, and by the prospects of staking out ground-floor positions in the emerging world of "cannabusinesses," they cultivate popular varieties of bud while experimenting with soils, temperatures, and light sources.

From the rear of the room, a baritone voice pipes up — a student remarking on the crystalline texture of the leaves when the plants are raised under light-emitting diodes. "With the LEDs, it just looks way frostier than anything under the high-pressure sodium," he says.

Details get technical, as in any science class, but the larger lesson is clear to see. Here, as in many other places across America, the future of cannabis is being sown — and, make no mistake, it is a future high on promise.

Oaksterdam takes its name from a bastardization of Oakland, where the university began, and pot-friendly Amsterdam. Here, new growers and dispensary operators are being trained like whole legions of Johnny Appleseeds, soon to spread pot's blessings from one coastline to the other. Not that anywhere is truly virgin ground, but consider: The pro-marijuana movement has never had an army so large, politically sophisticated, and well-funded, even if supporters downplay the millions that roll in. Nor has it enjoyed such a frenzied period of media exposure, a startling amount of it positive.

Never has there been such a concerted thrust to legalize the drug nationwide — for medical purposes, for the plain old joy of getting stoned, and for a gold mine in profits to be reaped by those who control the multipronged industry. Together with a rapidly shifting public attitude toward pot and a White House willing to accept state medical-marijuana laws, legalization seems as inevitable today as it was unthinkable a generation ago. "We're almost at a zeitgeist," says one of the high-profile lobbyists who is making it happen, Allen St. Pierre, executive director of the National Organization for the Reform of Marijuana Laws (NORML) in Washington, D.C.

Zeitgeist has become one of the buzzwords of the campaign — meaning, in context, a sort of coming together of favorable forces. St. Pierre, who can call on advisory-board input from the likes of Willie Nelson and Woody Harrelson, is a glib former altar boy and preppy from Massachusetts who likes to wear a marijuana-leaf lapel pin. He says that in the past year, NORML has seen an unprecedented escalation of Web-page hits, podcast downloads, new memberships, and media calls. "We monitor [newspaper] columns, and editors have swung in favor of reform," he says. "I will go give a lecture in Des Moines, Iowa. The questions people are asking come right out of watching Weeds on Showtime. It's quite remarkable."

Badgering newspapers and television programs to pay attention to the subject used to be one of the critical challenges for people like St. Pierre. Getting a meaningful dialogue started was half the battle. Now the buzz is self-sustaining, indicating a willingness of America, as a whole, to engage the subject.

"The first time, nearly eight years ago, I attempted to pitch a marijuana-related story to CNN, they literally laughed at me," remembers Bruce Mirken, a San Francisco–based spokesman for the Marijuana Policy Project. "The person who answered the phone burst out laughing. Now they're calling us. We've been on various broadcasts and cable network shows 21 times [in 2009] — at least a couple on CNN. We've also been on the Today show, ABC World News, really all over."

CNBC has run and rerun its recent documentary Marijuana, Inc.: Inside America's Pot Industry, exposing the booming pot trade and the sordid side of California's largest cash crop — the shootings, thefts, and arson fires; the homes in Humboldt and Mendocino counties gutted to make room for illegal indoor nurseries; and the secluded parcels of national forest planted with pot by Mexican cartels intent on cornering metropolitan markets.

In September, Fortune magazine ran the headline "How Marijuana Became Legal," as if the outcome of the fight were a fait accompli. "We're referring to a cultural phenomenon that has been evolving for 15 years," observed author Roger Parloff, who suggested that the critical, sea-changing climax might turn out to be a "policy reversal that was quietly instituted [this year] by President Barack Obama."

Ah, Obama. Many attribute a good share of the present impetus to Obama, the third president in a row to acknowledge smoking weed. Bill Clinton famously claimed he never inhaled. George W. Bush fessed up only after a private admission was secretly recorded and leaked to ABC News. Obama won the everlasting affection of the pro-pot crowd when he addressed the matter of inhaling and asked, "Isn't that the point?" He also elicited joyous whoops when he jettisoned existing Bush-era policy last fall and instructed Attorney General Eric Holder and the vast federal antidrug apparatus to stand down in the protracted war with states over medical marijuana. No longer would private holders of medical-marijuana cards have to fear being busted by federal agents after picking up a supply of kush from the corner dispensary. Nor would dispensary owners have to worry about the feds.

For the marijuana lobby and its broader aims, the win was gigantic. It removed — for the current presidential term, at least — the daunting specter of federal interference, and turned virtually the entire U.S. into one big, wide-open game board. Pot advocates divide that game board state by state, believing that the surest way to overcome conservative inertia that keeps pot outlawed is to spread legalization keyed to states' rights to craft their own statutes.