It hasn’t been a great fall for new programs on the broadcast nets, but ABC has fared the best. Now the Alphabet looks to have added another keeper in Monday comedy “Samantha Who,” which saw a strong second outing.

The Christina Applegate comedy, about a woman who suffers amnesia and gets a “do-over” on life, capitalized on a stronger delivery from lead-in “Dancing With the Stars” to match its premiere-week rating among young adults. Its demo score is the best for the second airing of an ABC half-hour comedy in four years.

“Samantha” joins Wednesday hours “Private Practice” and “Pushing Daisies” to give the Alphabet net the three strongest rookie performers of the season so far.

According to Nielsen’s “live plus same-day” DVR playback estimates, “Samantha Who” averaged a 4.5 rating/10 share in adults 18-49 and 13.68 million viewers overall — in line with its strong premiere averages (4.5/10, 14.42m). It ranked second in its timeslot in various categories and beat out rival laffer “Rules of Engagement” on CBS (3.9/9, 10.82m).

“Samantha” gave ABC its best 18-49 score for week two of a regular half-hour comedy since “I’m With Her,” which followed “8 Simple Rules” in fall 2003.

It benefited in week two from a stronger “Dancing,” as the hoofing skein was the night’s No. 1 show in 18-49 (5.5/13), 25-54 (6.8/15) and total viewers (21.37 million).

It’s been a struggle for ABC to gain much traction with half-hours this fall, but its momentum could be turning. “Cavemen” and “Carpoolers” opened well and then dropped off some, but they are hanging in there after three airings on Tuesday.

ABC also has “Notes From the Underbelly” on the bench; that show will likely be paired with “Samantha” at some point.

Elsewhere on the fifth Monday of the season, CBS laffers “How I Met Your Mother” (3.4/9 in 18-49, 8.50m) and “The Big Bang Theory” (3.5/9, 8.81m) have asserted themselves as the No. 2 choice in the 8 o’clock hour led by “Dancing.” That’s a reversal from earlier in the season, as dramas “Prison Break” on Fox (3.0/8, 7.44m) and newcomer “Chuck” on NBC (2.9/7, 7.22m) have both dropped off some.

“Chuck” continues to perform at a pretty good level at 8, but “Journeyman” hit a low at 10 (2.4/6, 6.06m). The time-travel rookie drama retained about half of its lead-in from “Heroes” (4.9/11, 10.81m), which has slipped after a strong season preem and hit a firstrun low.

ESPN won the night in 18-49 with its “Monday Night Football” matchup between Indianapolis and Jacksonville (5.1/13, 12.50m), while ABC prevailed in all female demos and total viewers.