Featuring spectacular views of the San Gabriel Mountains, Altadena was developed as a suburb of Pasadena in 1887. It has long refused annexation by neighboring Pasadena.

Altadena is part of the County of Los Angeles and is politically run by the Los Angeles County Board of Supervisors who have executive, legislative and judicial powers. There are five members of the Board of Supervisors, elected by geographic district. Altadena is in District five, presently represented by Supervisor Michael D. Antonovich. In the state legislature Altadena is located in the 21st Senate District, represented by Democrat Jack Scott, and in the 44th Assembly District, represented by Democrat Anthony J. Portantino.

In 1887 Andrew McNally, the printing magnate from Chicago and his good friend Col. G. G. Green had built mansions on what was to become Millionaire's Row, Mariposa Street near Santa Rosa. Newspaper moguls William Armiger Scripps and William Kellogg built side by side just east of Fair Oaks Avenue. The grandson of Andrew McNally, Wallace Neff, became a famous Southern California architect. He started his career in Altadena with the design and construction of St. Elizabeth of Hungary Catholic Church ( parish est.1918) which was dedicated in October 1926.