In addition to these works, Raposo also composed extensively for three Dr. Seuss TV specials in collaboration with the DePatie-Freleng Enterprises: Halloween Is Grinch Night (1977), Pontoffel Pock, Where Are You?

Raposo's decision to take Schwartz's suggestion and move in 1965 eventually led him to his fated meeting with Henson, to Sesame Street, and toward international fame.

He wrote the "Sesame Street Theme" – various versions of which have opened every episode – as well as many of its most popular songs, such as "Bein' Green", "C is for Cookie", "Sing" and "ABC-DEF-GHI".

According to his son Nicholas in a 2002 telephone conversation, Joe Raposo usually chose to portray anonymous, silly characters in these segments, which were nearly always produced on 16 mm film.

The Sesame Street character Don Music maintained a framed and autographed glamour photograph of Raposo on the wall of his Muppet atelier.

Raposo performed joke characters for film segments on The Electric Company similar in style to what he had done on Sesame Street.

One segment showed him attempting to get dressed in jacket and necktie against a white wall under the word "dressing", until the prefix "un-" appears and attaches itself to the prior word, forcing him to engage in a mock striptease which ends with him modestly hopping off-screen and tossing the remainder of his clothing into an empty chair left on-screen.

Other forays of his into the craft included both the tenor singing role of "master pickler" Gil Gickler in DePatie-Freleng's Dr. Seuss cartoon program Pontoffel Pock, Where Are You?

[7] Raposo also performed at least three other character voices in the cartoon, including a Groogen musician whose "flugel bugle" is destroyed by Pontoffel in an attack flyover,[8] as the ancient Senior Fairy above McGillicuddy who oversees the fairy squadron's worldwide search for the missing Pock and his piano, and as an angry Groogen dairywoman spilt milk upon by a too-close fly-by of Pontoffel's.

The musical was the first theatre company production from the United States to perform in the Soviet Union upon resumption of cultural relations between the two countries.

It was performed in concert on Broadway for one night only on December 12, 2005; the production starred Brian Stokes Mitchell, David Hyde Pierce, and Judy Kuhn.

During his career Raposo composed themes for several sitcoms such as Ivan The Terrible, Three's Company, The Ropers and Foot in the Door, film scores such as The Possession of Joel Delaney (1972), Savages (1972) and Maurie (1973), and documentaries, most notably Peter Rosen's production America Is for which Raposo not only scored a patriotic, critically well-received title theme but, unusually, served as its on-screen narrator.

Raposo also composed numerous other works influenced by Jones for Sesame Street, many featuring kazoo and other comical sound-effect objects and instruments like siren whistles, bulb horns, and tenor banjos.

For The Electric Company, particularly for songs he composed for the Short Circus, he led CTW to pop-record production values and generally strongly enforced an adult musical sophistication for all content he supervised.

Given an unusual creative freedom in the Music Department at 1970s CTW, Raposo toggled from convincing country ballads (e.g. "The Ballad of Casey MacPhee," which depicted Cookie Monster as a heroic train engineer caught in a mountain avalanche) and authentic hillbilly ("It's a Long, Hard Climb, But I'm Gonna Get There" and "My Favorite Letter P" among others) to blues elegies of considerable emotional and tonal complexity, like "New Life Coming" and "Bein' Green."

Themes written for muppet Roosevelt Franklin and the segment H exhibit some of Raposo's most convincing soul and funk composition and arrangement; the former contains clear allusions to the Philly Four and Lee Dorsey while the latter attempts coupling a convincing African-American Seventies funk bassline to the cycling musical structure of a European round, all while still somehow retaining his signature high end accents along the upper melodic ramparts of the composition.

[11][12] Raposo was a close friend of Frank Sinatra, Tom Lehrer, WNYC radio personality Jonathan Schwartz, and Academy Award-winning filmmaker Bert Salzman.