Born in the village of Leifiifi on the island of `Upolu, Semisi Ma`ia`i is a doctor of medicine and holds the Sāmoan orator's title, Papaāli`i. He emigrated to New Zealand in 1954 and, after graduation from medical college, married Jenny, a Pākehā New Zealander who was then working as a nurse in Wellington. They moved first to New Plymouth and then to Auckland, where they raised two children.
Semisi wrote his Sāmoan dictionary Tusi 'Upu Sāmoa over this period. Forty years later, in 2010, it was published by Little Island Press, the first such dictionary to be written by a Sāmoan. Semisi and Jenny now live in Wellington, where Semisi continues to write.