Fast National ratings for Monday, March 29, 2010.
 
ABC's "Dancing with the Stars" retained its premiere week heat, while "Castle" hit series highs as the network took advantage of CBS' repeats to dominate Monday night.
 
Among adults 18-49, ABC averaged a 4.9 rating, far ahead of CBS' 2.8 rating and the 2.2 rating for FOX. NBC's 1.8 rating was good for fourth in the key demographic, leaving The CW in fifth with a 0.9 rating.
 
Overall, ABC averaged an estimated 19.86 million viewers to go with a 12.5 rating/20 share. CBS was a distant second with a 5.2/9. FOX's 4.3/7 was third, beating the 3.4/6 for NBC. The CW's 1.2/2 trailed. 
 
In the 8 p.m. hour, ABC got a 13.3/21 from "Dancing with the Stars," which also did a 5.0 rating in the demo. CBS' "How I Met Your Mother" repeat (3.7/6) and a new "Rules of Engagement" (4.5/7) were second. In ratings, FOX's "House" repeat was third, but NBC's "Chuck" (3.3/5) drew more viewers and did a higher 18-49 rating, bumping up to a 2.1 rating after two down weeks. The CW's "Life Unexpected" had a 1.3/2 for fifth, moving back over 2 million viewers.
 
"Dancing with the Stars" improved to a 15.1/23 for ABC in its second hour, doing a 6.0 rating in the demo. CBS' repeats of "Two and a Half Men" and "The Big Bang Theory" were a solid second. FOX's "24" had a 5.1/8 and a 2.6 demo rating, as announcements of the show's upcoming conclusion failed to provide even a minor boost. NBC's "Trauma" had a 3.0/5 for fourth, with The CW's "Gossip Girl" doing a 1.1/2 for fifth.
 
In the 10 p.m. hour, ABC's "Castle" had a 9.2/15, with 14.47 million viewers and a 3.7 demo rating, all series highs. It helped that CBS' "CSI: Miami" aired a repeat, finishing second. NBC's new "Law & Order" did a 4.0/7 for third.
 
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.