How should a cyclocross jersey fit compared to a road jersey?

A CX jersey should fit slightly looser than a road race jersey—more like a club fit than an aero race fit. You need freedom of movement for running, jumping, and shouldering the bike. When trying one on, simulate running arm swing and shoulder the position of carrying a bike on your shoulder. If the jersey restricts these movements or rides up, it's too tight. The jersey should be close enough to avoid flapping but loose enough for full range of motion.