1525	Dioga da Rocha and his crew, sailing for Portugal, go ashore in Ulithi. They remain for four months, and possibly introduce the islanders to Catholicism.
1670s	Outer islanders from Yap and Chuuk, who had been trading regularly with the Marianas islands, stop sailing there because Spanish activity made it seem too dangerous. They had been trading turtle shells and cowrie shells for medicinal plants, dyes and pottery.
1686	Francisco Lazcano passes through and names the islands "Islas de Carolinas" (Caroline Islands), referring to all islands from Palau to Kosrae.
1712	Spanish Captain Bernard de Egui and his ship Santo Domingo kill three Ulithians.
1722-1731	Castaway Woleaians arrive on Guam and meet Father Cantova. They later embark for Ulithi, where Father Cantova is killed.
1805	Trade reestablished with the Marianas. The Outer Islanders trade seashells, turtle shells, woven mats, hemp and turmeric for iron, nails, knives, and copper.
1840s	Andrew Cheyne stays on Yap for two months, trying unsuccessfully to set up a trepang (sea cucumber) business. His crew brings an influenza epidemic to Yap, and fifty people of the Tomil district die. Cheyne escapes when Tomil chief Leok plans to kill him.
1871	Irish-American David Dean O'Keefe washes ashore on Yap, sole survivor of the shipwreck Belvedere. The Yapese treat him well and return him to health. German Alfred Tetens was running the first trading station on Yap, owned by Godeffroy & Son. Yap, at this time, is one of the busiest ports in the Pacific.
1875	O'Keefe opens his own trading company in Yap, taking Yapese to Palau on his ships to carve their stone money, in return for copra.
1885	Spain and Germany both claim the Caroline Islands. The pope issues a declaration giving Spain ruling power over the Carolines. Germany and Great Britain are allowed to trade. Spain sends a governor to Yap.
1880s	Spanish Capuchin missionaries establish a mission on Yap. A large earthquake occurs and Yapese think their traditional spirits caused it, because they were angry that the Yapese were listening to the Spanish Capuchins.

1899	After the Spanish-American War, Spain sells the Carolines to Germany. Arno Sefft becomes the first district administrator in Yap, overseeing the Western Carolines. He holds monthly meetings with the chiefs.
1900-1905	Germans establish Yapese police force, open post office and first hospital on Yap. They begin taxing the Yapese, who pay in copra or money or by working for the German government.
1905-1910	German Capuchin priests replace Spanish priests on Yap. First telegraph station opened in Colonia. Yapese and Outer Islanders begin working for Germans in Anguar phosphate mines.
1910-1915	Law of 1912 gives land ownership to islanders. German government promulgates rules on coconut cultivation. Breaking the rules can lead to a jail sentence.
1914	Japan peacefully takes Micronesia from the Germans when WWI begins. The Japanese Navy takes charge of administration, and begins building roads, wharves and docks throughout Carolines. Rice is introduced. Law allows Japanese men to marry Islander women, but not vice versa.
1915-1919	Japanese try to control and own all businesses. Most other foreign companies are forced to leave. Policy establishes free medical treatment for islanders.
1920-29	Micronesian districts officially under control of Japan following WWI. Japanese start bringing Chamorros from Saipan to Yap to work for the government. By Japanese request, the pope sends two Spanish Jesuits to Yap to replace departed German missionaries. Schools for islanders are opened, giving three or five years of primary education to islanders.
1930-1939	By 1935, Japanese and other foreigners outnumber Micronesians. Japanese military buildup begins, with military personnel taking government offices. Micronesians are sent to Angaur and Fais to work the phosphate mines, and receive lower wages than the Japanese. Colonia has been developed into a small Japanese town.
1942	Following the Japanese attack on Pearl Harbor, Japan starts drafting Micronesians into its military.
1944	U.S. begins its invasion of the Caroline Islands in 1944. First attacks on Ulithi in March of that year. By December, Ulithi is secured and becomes a home for the U.S. fleet. Islanders are moved and concentrated on Fedraey. U.S. bombs targets in Yap

1945-1947	With the end of the War, the U.S. takes control of Micronesia. The Trust Territory of the Pacific Islands (TTPI) is established by the United Nations and placed under U.S. administration.
1950s	Yap Trading Company (YTC) is established as a local business (1951). First Yap Islands congress convenes, with elected representatives (1959).
1960-1965	Congress of Micronesia established. Short-wave radios begin to be used to communicate with Outer Islands. Yap High School opens, 1962. Schools begin being built on Outer Islands, with Outer Island High School opening in 1963.
1966-1969	First Peace Corps volunteers arrive in Micronesia. Outboard motors start to become common. Yap District Legislature replaces Yap Islands Congress. Rai View, Yap's first hotel, opens. Continental Micronesia begins service to Yap.
1970s	E.S.A. Hotel opens on Yap. Television becomes available. Rice becomes a major part of the diet. Pacific Missionary Aviation (PMA) begins flights in Yap. Louis Rapanglug of Satawal navigates a traditional canoe between Satawal and Japan (1975). Mau Piailug of Satawal navigates the Hokule‘a between Hawai‘i and Tahiti (1977).
1978	TTPI districts vote on Micronesian constitution, leading ultimately to the formation of the Federated States of Micronesia (FSM). First elected governors take office in 1979 as FSM constitution comes into effect.
1980s	Yap State Constitution is ratified, and John Mangefel is first governor elected under it (1982). Compact of Free Association is approved by the U.N. Security Council (1986). Dating practices of young people begin to change towards more Western style, and fiberglass boats begin to replace wooden boats.
1987	Typhoon Orchid hits Ulithi, Fais, and Faraulap. Ulithi and Fais are declared disaster areas. Islanders receive money from FEMA to rebuild their houses. Many FSM citizens begin to migrate to Guam, Hawai‘i, Saipan and the U.S. Mainland.
1990	Typhoon Owen hits Outer Islands of Yap, except Sorol and Ngulu. FEMA helps rebuild houses on several islands. Number of hotel rooms in Yap grows from 26 to 44.
1991	FSM joins the United Nations, and adopts a national anthem.

1995	Yap State Public Utilities Corporation is formed to provide electricity and water to Yap Island and Ulithi, and electricity to Woleai. Yap Fresh Tuna Inc. beings operation.
1997	Internet service becomes available in the FSM, and the use of email begins.
1999	Yap State Department of Education changes its name to Yap State Education Enterprising Department (YapSEED).
2001	Ulithi Adventure Resort opens on Falalop.