I suppose one could say that the precursor to the ABC Afterschool Special was the "CBS Playhouse" which started airing stand alone made-for-tv movies as far back as 1967. One of it's earliest entries was a play by Ron Cowen entitled Saturday Adoption. This was Cowen's first credited script but he would go on to write notable episodes of one of my favorite shows FAMILY.
While I haven't seen this program, I did read the teleplay. It was reprinted in a 1971 edition of Scholastic Scope magazine, along with several original illustrations based on the show. (see below).
This coming-of-age story is notable because not only does it deal with the generation gap, but it also confronts racial issues as well. The main character is studying to be a lawyer but yearns to drop-out. He befriends an african-american teenager who he believes he can help. As the story progresses we are unsure as to who could make the best decision for whom. The author's message seems to be one that puts the individual in confrontation with society. Pretty edgy stuff for prime-time television at the time.
I believe programs such as this set the standard for discussions of the counterculture without necessarily providing any answers. I am a fan of these open-ended stories. Another one that played on TV just a few years later was The Neon Ceiling (1971). That one concerns a housewife and her teenage daughter who flee their boring lives to live with a drop-out in his desert diner.
(photo of Gig Young from The Neon Ceiling below)