queen consort of Philip V of Spain (reigned 1700–46), whose ambitions to secure Italian possessions for her children embroiled Spain in wars and intrigues for three decades. Her capability in choosing able and devoted ministers, however, brought about beneficial internal reforms and succeeded in improving Spain's economy.

Isabella was the daughter of Odoardo Farnese (died 1693), the eldest son of Ranuccio II of Parma and Píacenza. She was the second wife of Philip and arrived in Spain in December 1714, whereupon she dismissed the resident royal favourite and quickly established an ascendancy over her weak husband that she continued to exercise until his death in 1746.

Since Philip's two sons by his first wife were in line to succeed him, the ambitious Isabella sought to secure lands in Italy for the children (four sons and three daughters) she bore the sovereign. This quest dominated her reign, and in the end Spanish imperialism in Italy achieved marked success. Isabella's eldest son, Charles (afterward Charles III of Spain), and his brother Philip both gained titles to Italian domains.

Isabella favoured ministers who could acquire the resources needed to advance her schemes, and the men she chose not only carried out her foreign policy but also undertook useful economic, administrative, and military improvements. After Philip's death and the accession of her stepson Ferdinand VI (reigned 1746–59), Isabella ceased to exert any real influence and spent many of her later years away from court, although she did act as regent between the death of Ferdinand VI (August 10, 1759) and the arrival in Spain of his successor, Charles III, in December 1759.