In the ’60s, adherents posed Transcendental Meditation as a natural alternative to mind-expanding drugs like LSD. Now, proponents, including Mr. Lynch, argue that it can serve as an antidote to a stress-filled world, particularly for adolescents. Mr. Lynch cites his increasing concern for young people as the primary reason he launched his crusade.

“David has become a huge promoter of T.M.,” said Donovan, whose real name is Donovan Leitch. Mr. Leitch learned the practice from Maharishi himself, along with the Beatles, Mia Farrow and Mike Love of the Beach Boys, in Rishikesh, India, in 1968. Mr. Leitch added that Mr. Lynch has been able to “capitalize” on his fame and “redirect meditation back where it belongs, with the students.”

Transcendental Meditation faded from the pop culture landscape after the ’70s. Before Mr. Lynch, a marquee celebrity advocate was the illusionist Doug Henning, who died in 2000. But it hardly disappeared. Maharishi, now believed to be 90, still directs the movement, which claims more than 6 million adherents, from a log house on a 65-acre compound in the Dutch village of Vlodrop. The organization operates the Maharishi University of Management in Fairfield, Iowa; its own incorporated town, Vedic City (population 325), is nearby.

Over the years, the practice has been the subject of numerous scientific studies, including one by the University of Michigan Health System in 2003, which indicated that sixth graders who were practicing such meditation appeared to score significantly higher on tests of self-esteem and emotional competence.

But critics allege that it can inspire an unhealthy devotion. Rick A. Ross, who operates a nonprofit research organization in Jersey City called the Rick A. Ross Institute for the Study of Destructive Cults, Controversial Groups and Movements, said that the evidence he has studied indicates that Transcendental Meditation can be relaxing when not practiced excessively. But the movement fits some criteria he uses to define cults. It is “a personality-driven group, with Maharishi as its totalitarian leader,” Mr. Ross said, which at its extremes “can be seen as one in which people lose much of their ability for critical thinking.”

But Mr. Lynch, who was raised Presbyterian, insisted that Transcendental Meditation is neither a cult nor a theology, but simply a practice one learns, then pursues in private.