Philharmonia Baroque Orchestra is an orchestra based in San Francisco, which is dedicated to historically informed performance of Baroque, Classical and earlyRomantic music on original instruments. It was founded in 1981 by harpsichordist, teacher and early music pioneer, Laurette Goldberg (1932-2005). The ensemble added the Philharmonia Chorale in 1995.

Nicholas McGegan has been Music Director of Philharmonia Baroque since 1985. In addition, Philharmonia Baroque has welcomed eminent guest conductors to its podium including William Christie, Andrew Parrott, Jordi Savall, Gustav Leonhardt, Trevor Pinnock, Monica Huggett and Stanley Ritchie.

Philharmonia Baroque performs a seven-concert subscription season in three cities in the San Francisco Bay Area -- San Francisco, Berkeley, and Atherton/Palo Alto -- and is regularly heard on tour in United States and internationally. In 2005 Philharmonia Baroque debuted at the BBC Proms, Snape Maltings (UK) and the Concertgebouw in Amsterdam as part of its European tour. In August 2011, Philharmonia Baroque performed Handel’s opera Orlando at the Ravinia, Mostly Mozart, and Tanglewood festivals.

In 1990, Philharmonia Baroque began a successful collaboration with the Mark Morris Dance Group. Joint productions have included Purcell's Dido and Aeneas; Vivaldi'sGloria; Handel's L'Allegro, il Penseroso ed il Moderato; and Rameau's ballet-operaPlatée.

Philharmonia Baroque Orchestra has made a number of recordings for Harmonia Mundi,Reference Recordings and BMG and released a self-produced 2-CD set of music ofAlessandro Scarlatti on the Avie label. In 2011, Philharmonia Baroque launched its own CD label, Philharmonia Baroque Productions, and released three titles: a recording of Berlioz’ "Les Nuits d’été" and Handel arias featuring mezzo-soprano Lorraine Hunt Lieberson; a collection of three Haydn symphonies; and a recording of Vivaldi’s "The Four Seasons" plus three other violin concertos. Philharmonia Baroque is also featured in a monthly live radio program on the second Sunday of each month on KDFC-FM in the Bay Area.

Philharmonia Baroque was named "Ensemble of the Year" for 2004 by Musical America.