The National Survey on Drug Use and Health (NSDUH) asks persons aged 12 or older about their use of marijuana or hashish in the past year, including their frequency of use. This report focuses on how and where past year marijuana users aged 18 to 25 obtained their most recently used marijuana. Findings include estimates from the combined 2002, 2003, and 2004 NSDUH data. In 2002 to 2004, a majority (58.3 percent) of past year marijuana users aged 18 to 25 obtained their most recently used marijuana for free or shared someone else's, while 40.0 percent in this age group bought their marijuana. Three fourths (75.3 percent) of daily marijuana users aged 18 to 25 obtained marijuana the last time by buying it compared with one third (33.8 percent) of nondaily users. More than three fourths (78.2 percent) of the past year marijuana users aged 18 to 25 who bought their most recently used marijuana bought it from a friend. (Contains 7 endnotes and 3 figures.)