Fast National ratings for Monday, March 30, 2009.

"Dancing with the Stars" was dominant on Monday night, but a lackluster demographic performance from "Castle" helped FOX salvage a ratings split.

Among adults 18-49, FOX averaged a 4.2 rating, nipping CBS' 4.1 rating and the 4.0 rating for ABC in the key demographic. NBC was comfortably back in fourth with a 2.5 rating, which still beat the 1.2 rating for The CW.

Overall, though, ABC averaged an estimated 16.76 million viewers to go with a 10.8 rating/17 share. CBS was a distant second with a 7.3/11, edging out the 6.9/11 for FOX. NBC's 4.0/6 beat the 1.6/2 for The CW.

ABC was well in front to start with night, doing a 12.1/19 for "Dancing with the Stars" in the 8 p.m. hour. FOX was second with a 7.4/11 for a new "House." CBS averaged a 5.7/9 between "Big Bang Theory" and "How I Met Your Mother." NBC's "Chuck" had a 3.5/5 for fourth, more than doubling the total for The CW's "Gossip Girl." 

"Dancing with the Stars" improved to a 13.6/20 in its second hour for NBC. CBS' "Two and a Half Men" and "Rules of Engagement" finished second. FOX's "24" had a 6.5/10 for third, thumping the 3.9/6 for "Heroes" on NBC. Fifth place went to The CW's "One Tree Hill," which had a 1.7/2.

At 10 p.m. CBS took control with an 8.5/14 for "CSI: Miami." ABC's "Castle" had a 6.7/11, and tied for second with NBC's "Medium" in the key 18-49 demo.

All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.