“THE GIFT OF AMAZING GRACE,” Wednesday, 3-4...

“THE GIFT OF AMAZING GRACE,” Wednesday, 3-4 p.m. (7)(10), 4-5 p.m. (3)(42)--It’s a day for centennials on ABC and also on NBC.

NBC broadcasts the 100th episode of “St. Elsewhere” at 10 p.m. Wednesday, an amazing milestone for the medical drama considering its

inauspicious beginning four years ago. In one of the greatest demonstrations of faith in network annals, NBC renewed the show after its first season despite the fact that only eight of the 98 prime-time series that aired that year garnered smaller ratings.

“St. Elsewhere” hasn’t turned into a spectacular hit, but it has delivered consistently good drama, winning critical accolades for its actors and creative staff and respect for its network, for having the courage to gamble on quality.

So too with ABC’s “Afterschool Specials,” which marks its 100th broadcast Wednesday with “The Gift of Amazing Grace,” an hourlong drama about a family of gospel singers. This was a pioneering series when it debuted in October, 1972, serving up reality-based dramatic fare produced especially for children, and it still is tackling

subjects of concern to its young

audience.

Over the years the anthology series (which usually airs once a month during the school year) has dealt with everything from sex education to divorce, from drug and alcohol abuse to rape. Among the topics last season were child molestation and the homeless, and so far this season it has presented programs about teen-age suicide and teen-age fatherhood.

“The Gift of Amazing Grace” isn’t that serious, but it’s notable for its depiction of a family that isn’t in the TV mainstream: black, religious and involved with gospel music. The plot embraces their deliberation about whether to increase their chance of commercial success by also singing pop music.

“We were meant to sing gospel music--beautiful music,” argues one of the group.

“Anything beautiful has God in it,” counters Faith, the lead singer (Della Reese).

At the heart of the story is Faith’s niece, Grace (Tempestt Bledsoe, Vanessa on “The Cosby Show”), who is a reluctant backup singer in the group and wants out. Her dilemma is that her father’s and aunt’s identities are so closely tied to the music that a rejection of the work is taken as a rejection of the family.

The themes--about striving for acceptance, being true to yourself, being honest in your relationships, the need for family--are pertinent to young people, and while the resolution is uncommonly simplistic compared to the best of the “Afterschool Specials,” it nevertheless gives its viewers a hopeful portrait of a teen-ager taking charge of her life.

That model has been the common thread running through all 100 “Afterschool Specials,” and their most valuable contribution.