wide-eyed charm captured the hearts of millions of girls worldwide. >> you're taking is auto shop. >> me, too. >> the parred ridge family, a musical sit-com about a family and a rock 'n' roll band gave him a national audience for his own music. ♪ i think i love you >> i think i love you, the show's first single, topped the billboard 100 in 1907 and sold over 5 million copies. >> i was always a musician but i never pursued my career as a musician. it was just fate the way the stars aligned themselves. >> reporter: cassidy's wispy voice and wholesome persona broke out from the small screen into sold out arenas around the globe. his fan club at one time reportedly had had more members than elvis or the beatles. in 1972, at the height of his partridge family fame, he began to shift away from his squeaky clean image appearing naked on the cover of "rolling stone"