On First Circle, the Group used instruments it hadn't recorded with before, including the sitar ("Yolanda, You Learn"), trumpet ("Forward March"), and agogo bells ("Tell It All"). The first song, "Forward March", with Lyle Mays on trumpet, uses dissonant, out-of-tune chords and shifting time signatures. On puttiing the song first, Metheny remarked that it "seemed like a good idea at the time." 
This was the first Group album to feature a song with written lyrics, "Más Allá," by Aznar.
First Circle expanded the scope of the Group's music. In a podcast retrospective, Metheny remarked that the album brought the Group to a creative high that he had been seeking since its foundation. "With the record, First Circle, I finally felt like the Group was what I hoped it might be someday...there was this feeling of, 'Okay, we've done it. We can go anywhere now.'" He stated that First Circle, Still Life (Talking), and Letter from Home, among the Group's most popular albums, were part of a trilogy connected by their musical explorations and accessibly melodic personalities.
With "Phase Dance" and, "Are You Going With Me?" the album's title track, "The First Circle", became one of the Group's most popular songs.