Cool Stars 14 - Submitted Abstract # 276 This version created on 05 October 2006 Rotation in Young Stars Luisa Rebull, Spitzer Science Center John Stauffer, Spitzer Science Center Steve Strom, NOAO Sidney Wolff, NOAO The smallest molecular cores observed to date have at least ~6 orders of magnitude greater angular momentum per unit mass than the Sun, sugggesting that they would greatly exceed the breakup velocity if no angular momentum was lost during the star formation process. Therefore, an angular momentum regulation mechanism must be at work in the pre-main-sequence phase, and disks are often invoked as the solution to the angular momentum problem. Thanks to large-format CCDs, more than 1000 periods for young stars are now known (with more being presented at this conference), and with the Spitzer Space Telescope, we have the ability to get reliable circumstellar disk indicators for many 1000s of stars at once. Now, for the first time, we may have enough stars to start to constrain the angular momentum loss mechanism in a meaningful fashion. In this talk, I will review the observations made to date of rotation in pre-main-sequence low-mass stars. ----------------------------------