|Aloha Community Library||Aloha Community Library Association|
|Banks Public Library||City of Banks|
|Beaverton City Library||City of Beaverton|
|Beaverton-Murray Scholls Library|
|Cedar Mill Community Library||Cedar Mill Community Library Association|
|Bethany-Cedar Mill Library|
|Cornelius Public Library||City of Cornelius|
|Forest Grove City Library||City of Forest Grove|
|Garden Home Community Library||Garden Home Community Library Association|
|Hillsboro Brookwood Library||City of Hillsboro|
|Hillsboro Shute Park Library|
|North Plains Public Library||City of North Plains|
|Oregon College of Art & Craft Library||Oregon College of Art & Craft|
|Sherwood Public Library||City of Sherwood|
|Tigard Public Library||City of Tigard|
|Tualatin Public Library||City of Tualatin|
|Tuality Health Resource Center||Tuality Community Hospital|
|West Slope Community Library||Friends of West Slope Community Library|
Past WCCLS-affiliated libraries included ones in the former Tanasbourne Mall (when the Tanasbourne area was unincorporated) and, in the 1970s, Aloha Park Library, located in Aloha Park school, which was open to the public one night a week.
- "Overview of Library Services". Washington County Cooperative Library Services. Retrieved December 11, 2012.
- Gardner, Fran (January 11, 1976). "New network ties together all the county's libraries". The Valley Times. Beaverton, Oregon. p. 10.
- "Library Map and Listing". Washington County Cooperative Library Services. Retrieved January 9, 2016.
- "Aloha Community Library". Washington County Cooperative Library Services. Retrieved January 9, 2016.
The passage of Measure 34-235, the countywide library replacement levy, will allow the Aloha Community Library to become a full member of the Washington County Cooperative Library Services in 2016 and receive operating funds from WCCLS. The target date for this is September 2016.