Not everyone at a gathering has the same reaction to the sight, or should I say stink, of marijuana. Some will lick their lips in anticipation of being propelled into a delicious psychosocial gavotte. Others will frown or skitter away, fearful they’re about to find out why the word “dude” is sometimes spelled “doood.” Some will simply think, “Midnight Express.”

The etiquette of pot smoking in social settings is largely uncodified. Yet the world needs an Emily Post to hack a pathway through this fuggy thicket, particularly given pot’s increased presence in the mainstream. The recreational use of marijuana is now legal in two states, as is the medicinal use of it in 18 states and the District of Columbia. In 2010, there was the publication of “The Cannabis Closet,” a collection of testimonials from ganja-loving top executives and government employees and responsible parents, all of which had appeared on the writer Andrew Sullivan’s blog. The thicket: it grows ever thicketier.

If there are no children present, is it appropriate for a host to ask guests if they want to get high? Some people think that doing so puts the invited on the spot. “I just keep a decorative bong on a shelf in my living room,” said Rick Steves, who lives in Edmonds, Wash., and is the host of the public television show “Rick Steves’ Europe.” “If someone comments on it, then it opens up the conversation.” Asserting that liquor is better than pot for social lubrication, he added: “It’s rude to break up a party by bringing out the pot. Especially for nonsmokers, it can be awkward. If one spouse smokes and the other doesn’t, it’s like, ‘O.K., we’re not on the same wavelength, party over!’ ”

Other marijuana enthusiasts believe that Mr. Steves’s view regarding the incongruity between a THC-fueled guest and a non-THC-fueled one is overstated. Bill Maher, the host of “Real Time With Bill Maher,” said: “Alcohol is the substance where people feel the most uncomfortable when the other person isn’t also consuming it. I can’t tell you how many times someone has said to me, ‘I won’t drink if you don’t.’ ”