The death was confirmed by Abington Health Lansdale Hospital. The cause was acute respiratory failure, The Philadelphia Inquirer reported.
The Three Degrees formed in the early 1960s when Ms. Pinkney, who was still going to Overbrook High School in Philadelphia, joined with Shirley Porter and Linda Turner under the management of Richard Barrett, the record producer behind the Chantels and Little Anthony and the Imperials.
For more than a decade, Ms. Pinkney was the one constant in a group whose members came and went. She sang on the groups first single, “Gee Baby (Im Sorry)", on its 1970 hit Maybe and on the hits for Philadelphia International Records in the 1970s that helped the define the Philadelphia sound.
In a statement, Kenneth Gamble and Leon Huff, the labels founders, called the Three Degrees our Philly sound version of Motowns Supremes, but bigger and stronger and melodic.
The groups first two singles for Philadelphia International, “Dirty Ol Man" and “I Didnt Know", were modest successes, but “T.S.O.P.", a mostly instrumental piece featuring the studio band MFSB, reached No. 1 on both the R&B and pop charts in 1974. “When Will I See You Again?", which sold more than two million records, reached No. 2 on the pop charts that year.
