The Spanish match was a proposed marriage between Prince Charles, the son of King James VI & I of Kingdom of Scotland and England, and Infanta Maria Anna of Spain, the daughter of Philip III of Spain. Negotiations took place over the period 1614 to 1623, and during this time became closely related to aspects of British foreign and religious policy, before breaking down completely.

The policy, unpopular with England's Protestant House of Commons, where the recent Anglo-Spanish War (1585–1604) had not been forgotten, was initiated during the embassy to England of Diego Sarmiento de Acuña, conde de Gondomar, who arrived in London in 1614 with the offer that Spain would not interfere with James's troubled rule in Ireland if James would restrain the English "privateers" in Spanish American waters. Further, he proposed a marriage alliance, offering a dowry of £500,000 (later increased to £600,000), which seemed especially attractive to James after the failure of the Parliament of 1614 to provide him with the financial subsidies he requested.

The climax of the ensuing decade of high-level negotiation to secure a marriage between the leading Protestant and Catholic royal families of Europe occurred in 1623 in Madrid, with the embassy of the Prince Charles and James's favourite, George Villiers, 1st Duke of Buckingham. The wedding never took place despite the signing of a marriage contract by King James; criticism instead led to the dissolution of Parliament.

A Spanish marriage for Henry Frederick, Prince of Wales, Charles's elder brother who had died in 1612, had been proposed by his mother Anne of Denmark. After his death she supported the idea of a Spanish marriage for her daughter Elizabeth, but in 1613 Elizabeth married a prominent Protestant German prince. For her second son Charles, there were candidate marriages mooted from Savoy and Tuscany, as well as Spain and France. From 1614 to her own death in 1619, Queen Anne gave some support to a Spanish match, preferring at times a French marriage, and recognising that the Spanish proposals were entirely based on self-interest. A point brought up against it in 1620 was that the previous "Spanish matches", those that had brought Catherine of Aragon to England, and Philip II of Spain to marry Mary I, had in the popular memory turned out badly.

At the beginning of 1618 James I and VI was in a strong diplomatic position. His efforts against wars in Europe had been largely effective, and his own status as a Protestant ruler who was on good terms with Catholic powers was high. Success in reducing the religious factor in international relations then deteriorated for James, in parallel with the failure of the Spanish match, with the onset of the Thirty Years' War. In 1618 he was still concerned with detailed moves to improve his relationship with Spain, such as the translation of the anti-Calvinist Bishop Lancelot Andrewes, and the execution of the buccaneering Sir Walter Raleigh.

On the domestic front, the prospect of a Spanish dowry from a marriage between his heir Charles, Prince of Wales from 1616, and Infanta Maria Anna of Spain, was a potential source of income for James, who sought ways to rule without depending on the Commons for subsidies. The policy of the Spanish match was supported by the Howards and other Catholic-leaning ministers and diplomats—together known as the "Spanish Party"—but deeply distrusted by some Protestant groups in England. Sentiment was voiced vociferously in the Commons when James called his first parliament for seven years in 1621 to raise funds for a military expedition in support of Frederick V, Elector Palatine, his son-in-law.

There was in fact no chance that Pope Paul V would have issued the required dispensation for the Infanta to marry a Protestant. This fact was known to the Spanish king, but apparently Gondomar was kept in ignorance of the correspondence. Paul V died early in 1621, and his successor Pope Gregory XV was thought amenable to the idea of the match. James sent George Gage to Rome to lobby, putting the case on behalf of English Catholics. The matter was passed to a small group of cardinals, who emphasised that improved treatment for English Catholics was a prerequisite.

By the 1620s, events on the continent had stirred up anti-Catholic feeling to a new pitch. A conflict had broken out between the Catholic Holy Roman Empire and the Protestant Electoral Palatinate, when the Bohemians deposed Ferdinand II, Holy Roman Emperor as their king and elected James's son-in-law, Frederick V, Elector Palatine, in his place, triggering the Thirty Years' War. James reluctantly summoned parliament as the only means to raise the funds necessary to assist his daughter Elizabeth and Frederick, who had been ousted from Prague by Emperor Ferdinand in 1620. The Commons on the one hand granted subsidies inadequate to finance serious military operations in aid of Frederick, and on the other called for a war directly against Spain.