Turning Monticello into a neoclassical masterpiece in the Palladian style was his perennial project.[58] On January 1, 1772, Jefferson married his third cousin[59] Martha Wayles Skelton, the 23-year-old widow of Bathurst Skelton, and she moved into the South Pavilion.[60][61] She was a frequent hostess for Jefferson and managed the large household. Biographer Dumas Malone described the  marriage as the happiest period of Jefferson's life.[62] Martha read widely, did fine needlework, and was a skilled pianist; Jefferson often accompanied her on the violin or cello.[63] During their ten years of marriage, Martha bore six children: Martha "Patsy" (1772–1836); Jane (1774–1775); an unnamed son who lived for only a few weeks in 1777; Mary "Polly" (1778–1804); Lucy Elizabeth (1780–1781); and another Lucy Elizabeth (1782–1784).[64][d] Only Martha and Mary survived to adulthood.[67]

Jefferson's daughter Martha Martha's father John Wayles died in 1773, and the couple inherited 135 slaves, 11,000 acres (45 km2; 17 sq mi), and the estate's debts. The debts took Jefferson years to satisfy, contributing to his financial problems.[60]
Martha later suffered from ill health, including diabetes, and frequent childbirth further weakened her. 