The Bourbons, with the accession of Philip V of Spain, inherited the strongest claim to the Italian territories of the Spanish Crown. The Treaty of Utrecht of 1713 formalised the strict separation of the French and Spanish thrones under one head, and similar arrangements would later keep the thrones of the Two Sicilies and Parma (initially awarded to Austria) separate from the Spanish throne. After Spain’s victory over the Austrians at the battle of Bitonto in 1734, it was deemed diplomatically unwise to re-unite Naples and Sicily directly to the Spanish Crown, so a separate Neapolitan branch of the House of Bourbon was established in the person of the King’s younger son, Charles (King Charles VII of Naples, V of Sicily), and following Charles’ subsequent accession to the Spanish throne in 1759 (as Charles III), he was required, by the Treaty of Naples of 3 October 1759, to renounce Naples and Sicily in favour of his own younger son, who became Ferdinand IV. This chapter examines the interplay between the various branches of the Spanish and Italian Bourbons, showing how the balance of power and alliances shifted within the dynasty across the period. At the start, in the 1730s, Queen Elizabeth Farnese was successful in bringing back southern Italy into the orbit of Spain, at the expense of the Habsburg Monarchy. By 1768, however, the situation had reversed: with the marriage of King Ferdinand IV and the Archduchess Maria Carolina of Austria, Bourbon identity in Naples was significantly affected through a strong rapprochement to the court of Vienna led by the new queen.