Matthew Fox (<I>Lost</i>) and Katherine Heigl (<I>Grey's Anatomy</i>) Matthew Fox (Lost) and Katherine Heigl (Grey's Anatomy)

When will Lost drop its biggest boom of its penultimate season? When will the Walkers engage in their final family squabble? When will the good docs of Seattle Grace scrub out for the summer?

ABC has released a bevy of season finale dates — as well as locked in a pair of returns. Grab your calendar, a pen, and take note. (All dates are season finales, except where noted.)

Wednesday, April 29: Better Off Ted (series premieres March 18) 

Thursday, April 30: In the Motherhood (series premieres March 26), Samantha Who? (season resumes March 26) and Private Practice

Friday, May 1: Wife Swap and Supernanny

Tuesday, May 5:  According to Jim (series finale)

Wednesday, May 6: Scrubs (series finale; two episodes)

Thursday, May 7: Ugly Betty resumes season

Sunday, May 10: Brothers & Sisters

Monday, May 11: Castle

Tuesday, May 12: Cupid (series premieres March 31)

Wednesday, May 13: Lost (two-hour season finale)

Thursday, May 14: Grey's Anatomy (two-hour season finale)

Friday, May 15: America's Funniest Home Videos

Sunday, May 17: Extreme Makeover: Home Edition and Desperate Housewives (both have two-hour season finales)

Monday, May 18: The Bachelorette premieres new season

Tuesday, May 19: Dancing with the Stars (two-hour season finale)

Thursday, May 21: Ugly Betty (two-hour season finale)