National Association of Rocketry (NAR) – World’s oldest and largest nonprofit supporting model and high power rocketeers.
The American Rocketry Challenge (TARC) – World’s largest model rocket contest for middle and high school students.
Woodstock Challenger Learning Center – Inspiring students to pursue STEM careers and spark a passion for learning.
The Rocketry Forum – Devoted to all model and high power rocketry interests.
Ye Olde Rocketry Forum – Family friendly, with emphasis on earlier model rocket designs and kits.
Jim Z’s Rocket Plans – Featuring plans and decals for hundreds of current and out of production model rocket kits.
Open Rocket – Rocket design and simulation program; FREE!
Rocketry Reviews – Reviews and ratings on over 5,000 model rocket kits and accessories, RockSim and Open Rocket files.
ThrustCurve.org – Manufacturer specifications, certified performance data and other info on commercial model rocket motors and high-power rocket motors. Most importantly, you can download thrust curves for use with rocket flight simulators including Open Rocket and RockSim.