"Music to Watch Girls By" was the first Top 40 hit by Bob Crewe using his own name, recorded by his group The Bob Crewe Generation. Crewe first heard the song performed in a "jingledemo" for a Diet Pepsi commercial. Music was composed by Sidney "Sid" Ramin. The "big-band, horn driven" recording went to #15 on the pop chart and #2 on the Easy Listening chart. According to Greg Adams, writing for All Music Guide, the song "exemplified the groovy state of instrumental music at that time." In Bob Crewe's version, a trumpet plays the whole song , the first time around, sounding like Herb Alpert's Tijuana Brass style. The second time the instrumental is played, a half step up in tone from G Minor to A-Flat Minor, a Tenor Saxophone plays a more jazzier version, accompanied by strings and a harpsichord, that play a counter-melody. The trumpets finish up the refrain, and all of the parts are played, repeating the first part in the Coda, before the fade.