Collin County Texas Index of Landmarks & Vanished Communities
- Location information for landmarks and vanished communities in the county.
- http://www.rootsweb.com/~txlndmrk/collin.htm

Butterflies of Collin County, Texas
- Information about and pictures of all the known species of butterflies in the county.
- http://www.butterfliesandmoths.org/map?dc=5516&_dcc=1&si=44

Handbook of Texas Online: Collin County
- Current and historical information about the county.
- http://www.tsha.utexas.edu/handbook/online/articles/CC/hcc16.html

Prairie and Timbers Audubon Society
- Chapter of the National Audubon Society, located in McKinney, Texas.
- http://prairieandtimbers.org/

League of Women Voters of Collin County
- Non-partisan organization encouraging informed and active participation of citizens in government.
- http://www.lwvcollin.org/

Amphibians and Reptiles in Collin County
- Texas Cooperative Wildlife Collection list of species found in the county.
- http://wfscnet.tamu.edu/tcwc/checklist/COLLI043.HTM

Native Plant Society of Texas: Collin County Chapter
- Includes contact information and a schedule of meetings.
- http://lonestar.texas.net/~jleblanc/npsot_collincounty.html

Collin County Psychological Association
- Provides information to both Psychologists and people needing their services.
- http://www.psychselect.com/ccpa/

Collin County Law Enforcement Academy
- General information plus class schedules and on-line registration.
- http://www.cclea.org/

Rape Crisis Center of Collin County
- Information on the effects of all types of sexual assault, and the services that the center provides. All information is available in English and Spanish.
- http://www.rcccc.org