The roots of the Album Oriented Rock (AOR) radio format began with programming concepts rooted in 1960s idealism. The Freeform or Progressive formats developed the repertoire and set the tone that would dominate AOR playlists for much of its heyday.

In the mid to late 1960s, the FCC enacted a non-duplication rule prohibiting FM radio stations from merely running a Simulcast of the programming from their AM counterparts. Owners of AM/FM combo stations fought these new regulations vigorously, delaying the new rules for eighteen months. When finally enacted, station owners were pressed to come up with alternate programming options quickly.

The Freeform format in commercial radio was born out of this desperate need to program the FM airwaves, inexpensively. Programmers like Tom Donahue at KMPX developed stations where DJs had freedom to play long sets of music, often covering a variety of genres. Songs were not limited to hits or singles; indeed the DJs often played obscure or longer tracks by newer or more adventurous artists than heard on Top 40 stations of the day. This reflected the growth of albums as opposed to singles as rock's main artistic vehicle for expression in the 1960s and 1970s.

With a few exceptions commercial Freeform had a relatively brief life. With more and more listeners acquiring FM radios, the stakes became higher for stations to attract market share so that they could sell more advertising at a higher rate.

By 1970 many of the stations were moving to institute programming rules with a "clock" and system of "rotation". With this shift, Stations formats in the early 1970s were now billed as Progressive. DJs still had much input over the music they played, and the selection was deep and eclectic, ranging from folk to hard rock with other styles such as Jazz fusion occasionally thrown in.

A broad cross section of rock music that gained popularity during this time came to be called Progressive rock, likely because the wide recognition and success of artists could be attributed to airplay on Progressive stations; much the way the College rock label was given to bands that received air play on student-run college stations during the 1980s.