Only an intermittently diligent genealogist, Howard Phillips Lovecraft was able to discover little about the paternal side of his ancestry beyond the notes collected by his great-aunt Sarah Allgood. Subsequent genealogical research has failed to verify much of this information, especially regarding the Lovecrafts prior to their coming to America in the early nineteenth century. According to the Allgood notes, the Lovecraft or Lovecroft name does not appear any earlier than 1450, when various heraldic charts reveal Lovecrofts in Devonshire near the Teign. Lovecraft's own direct line does not emerge until 1560, with John Lovecraft.

The paternal line becomes of immediate interest only with Thomas Lovecraft (1745–1826), who apparently lived such a dissolute life that he was forced in 1823 to sell the ancestral estate, Minster Hall near Newton Abbot. According to Lovecraft (or the notes he was consulting), Thomas Lovecraft's sixth child, Joseph S. Lovecraft, decided in 1827 to emigrate, taking his wife Mary Fulford and their six children, John Full, William, Joseph, Jr, George, Aaron, and Mary, to Ontario, Canada. Finding no prospects there, he drifted down to the area around Rochester, New York, where he was established by at least 1831 as a cooper and carpenter.

Lovecraft's paternal grandfather was George Lovecraft, who was probably born in 1818 or 1819. In 1839 he married Helen Allgood (1821–81) and lived much of his life in Rochester as a harness maker. Of his five children, two died in infancy; the other three were Emma Jane (1847–1925), Winfield Scott (1853–1898), and Mary Louise (1855–1916). Winfield married Sarah Susan Phillips and begat Howard Phillips Lovecraft.

Lovecraft appears to have been much more industrious in tracking down his maternal ancestry, but again his conclusions are not always to be trusted. At various points in his life he traced his maternal line either to the Rev. George Phillips (d. 1644), who in 1630 left England on the Arbella and settled in Watertown, Massachusetts, or to Michael Phillips (1630?–86) of Newport, Rhode Island. Whatever the case, Asaph Phillips (1764–1829), probably Michael's great-great-grandson, headed inland and settled around 1788 in Foster, in the west-central part of the state near the Connecticut border.