The following groups and societies are excellent resources in learning more about Colorado's geology and paleontology.
 

Western Interior Paleontological Society (WIPS) - Lectures, symposiums, field trips in Colorado and neighboring states and a monthly Trilobite Tales newsletter.  Focuses primarily on paleontology, but all earth science topics are encouraged including: geology, paleoarcheology, etc.  Offers grants and scholarships in related studies.  Links to members websites.

Colorado Scientific Society - Lectures, symposiums, field trips in Colorado, family night, annual dinner, monthly newsletter.  Focuses primarily on Colorado geology, but broader mission includes a general promotion of knowledge and the understanding of science. Offers research grants to graduate students.

Friends of Dinosaur Ridge - Part of the Morrison Fossil Beds National Natural Landmark.  Outdoor museum located near Morrison, CO. Features Jurassic dinosaur bones and over 300 Cretaceous dinosaur footprints.  Group devoted to protecting resources at Dinosaur Ridge.  Offers field trips, educational classes and walking tours, interpretive trail guide.

Friends of Florissant Fossil Beds - Group devoted to assisting the National Park Service in its mission to preserve and protect the fossils beds near Florissant, CO.  Offers field seminars, interpretive programs, publications, financial support for related monument programs, etc.

Rocky Mountain Association of Geologists - Promotes interest in area geology and allied sciences.  Offers lectures, publications, monthly Outcrop newsletter, quarterly Mountain Geologist journal, field trips, continuing education courses.

North Jeffco Gem & Mineral Club - North Jefferson County Colorado.  Promotes earth sciences, rockhounding (rocks, minerals & fossils), diverse geology, etc.  Field trips in Colorado and neighboring states.  Monthly newsletter.