Marianna Martines (1744-1812) was a highly celebrated composer, singer, and keyboardist during her lifetime in Vienna, praised by such dignitaries as Dr. Charles Burney, and achieving the honor of being the first woman composer to be admitted to the Accademia Filarmonica di Bologna in 1773. She composed both large-scale and smaller works, including masses, oratorios, keyboard sonatas and concerti, cantatas, and arias. Yet today, despite a revival of interest in this important composer, she remains largely unknown and her nearly 70 surviving works remain all too underperformed. The purpose of this dissertation is to add to the existing scholarship by exploring the first movement of her Harpsichord Sonata in G Major, the last of her three extant sonatas, which is marked Allegro brillante, and is indeed a work of technical brilliance and difficulty, through various theoretical frameworks. This study demonstrates the extraordinary nature of this work by invoking classical formal theory, topic theory, with particular emphasis on the "brilliant" and "singing" styles, and the more recent feminist studies illuminating gender-coding in music. This theoretical analysis is considered against the backdrop of sociological studies examining the gender politics of Vienna and other parts of Europe during this time period. This study …