Originally Posted by Stewie
Or just get one of the myriad chili powders from Penzey's.
It'll keep longer (and IMO taste better) if you'll buy the dried chilies and roast, grind as needed. Once ground as in the powders, the flavor starts to dissipate. After about 6 months, there's not much left. Dried chilies will last at least a year, and dried whole spices will last much longer if kept in the freezer.