As announced, Jay Leno returns to host “The Tonight Show” (10:35 p.m., NBC). Will all be forgiven, if not forgotten? His guests tonight include Jamie Foxx, Lindsey Vonn and Brad Paisley.

For all of the talk about Jay vs. Conan, the greatest damage done by the Leno experiment was to NBC’s prime-time lineup. How much was the success of “The Good Wife,” the growth of “The Mentalist” and the mere survival of “The Forgotten” due to the weak competition from NBC? And will viewers follow NBC’s late-night dramas when they return to their proper time? The experiment starts tonight with a double dose of “Law & Order” and continues tomorrow with the introduction of “Parenthood” at 9 p.m.

• “American Experience” (8 p.m., PBS, check local listings) challenges the traditional view of the 19th century and the notion that history of that period was made only by men. A colorful profile of Dolley Madison makes an entertaining use of actors in period garb reading from her diaries and correspondence and re-enacting pivotal moments in her public and private life.

Madison emerges here as more than the name on a brand of snack foods. We’re told that she all but invented the role of first lady and had a deep understanding that politicians — and particularly those feuding in public — needed a social forum where they could mingle socially and cordially over drinks and the ameliorating presence of their wives.

As we’re reminded here, the young American republic had no rules of decorum. The first two presidents were seen as hewing too closely to England in their sense of majesty. Taking the opposite ap-proach, Jefferson seemed to throw protocol out the window, a gesture visiting dignitaries perceived as more rude than democratic.

It would take Dolley Madison, a fashionable clothes-horse and enthusiastic correspondent and gossip, to synthesize these two approaches and establish social customs that survive to this day.

• “The Bachelor” (7 p.m., ABC) comes to its conclusion and reconvenes for an immediate recap (9 p.m.). Throughout the evening, Tom Bergeron will pop up to announce the new lineup of “Dancing with the Stars.”

Tonight’s other highlights

• Director James Cameron (“Avatar”) appears on “Inside the Actors Studio” (6 p.m., Bravo).

• Chuck offers to make dinner on “Chuck” (7 p.m., NBC).

• Wilson and House bet on a patient’s diagnosis on “House” (7 p.m., Fox). Alfred Molina guest stars.

• Difficult deliveries loom large on Discovery Health’s “Baby Week,” beginning with “Paralyzed and Pregnant with Twins” (7 p.m.).

• Jeff receives unexpected attention on “Rules of Engagement” (7:30 p.m., CBS). Now in its fourth season.