The North American Syringe Exchange Network (NASEN), based in Tacoma, Washington, is an organization dedicated to supporting syringe services programs (SSPs) across North America. NASEN operates the Tacoma Needle Exchange and provides critical assistance to SSPs through loan assistance, fiscal sponsorship, program start-up kits, and lower-cost harm reduction supplies via the NASEN Buyers Club. Established in 1988, NASEN is a pioneer in the field, with the Dave Purchase Project playing a key role in the distribution of syringes in Tacoma.

The NASEN Directory, created in 1992, is the oldest and most comprehensive list of SSPs in the United States, U. S. Virgin Islands, and Puerto Rico.

However, it's important to note that the directory does not include all SSPs in operation. SSPs listed in the directory are a highly selected subset, mainly members of the NASEN Buyers Club, that have given their consent to be listed. The NASEN Directory serves as a valuable resource for those seeking information on syringe services programs and aims to promote harm reduction initiatives for individuals who inject drugs