May is Asian Pacific American Heritage Month. The month of May was chosen to commemorate the immigration of the first Japanese to the United States on May 7, 1843, and to mark the anniversary of the completion of the transcontinental railroad on May 10, 1869; the majority of the workers who laid the tracks on the project were Chinese immigrants. May is also Older Americans Month, established in 1963 to honor the legacies and contributions of older Americans and to support them as they enter their next stage of life; Jewish American Heritage Month, which recognizes the diverse contributions of the Jewish people to American culture; and Mental Health Awareness Month or Mental Health Month, which aims to raise awareness and educate the public about mental illnesses and reduce the stigma that surrounds mental illnesses.  

 May 1 is Beltane, an ancient Celtic, Pagan, and Wiccan holiday commemorated about halfway between the spring equinox and summer solstice; the day is often used to celebrate love and romance. May 3 is  Feasts of Saints Philip and James, a Roman rite feast day held on the anniversary of the dedication of the Church to Saints Phillip and James in Rome. May 4 is National Day of Prayer, a day of observance in the United States when people are asked to “turn to God in prayer and meditation.” May 5 is Cinco de Mayo, a Mexican holiday commemorating the Mexican Army’s 1862 victory over France at the Battle of Puebla during the Franco-Mexican War (1861–1867). May 8 to 9 (sundown to sundown) is Lag BaOmer, a Jewish holiday marking the day of Hillula of Rabbi Shimon bar Yochai.

 May 17 is International Day Against Homophobia, Transphobia, and Biphobia, a global celebration of sexual orientation and gender diversities. May 18 is Ascension of Jesus or Ascension Day, celebrated as the ascension of Christ from Earth in the presence of God within most of the Christian faith. May 19 is Malcom X Day, a holiday celebrated either on May 19th, his birthday, or on the third Friday in May, to commemorate the Civil Rights leader. May 21 is World Day for Cultural Diversity for Dialogue and Development, a day set aside by the United Nations as an opportunity to deepen our understanding of the values of cultural diversity and to learn to live together in harmony. May 23 to 24 (sundown to sundown) is Declaration of the Báb, the day of declaration of the Báb, the forerunner of Bahá’u’lláh, the founder of the Bahá’í faith. May 26 is Buddha Day (Vesak or Visakha Puja), a Buddhist festival that marks Gautama Buddha’s birth, enlightenment, and death; it falls on the day of the full moon in May and is a gazetted holiday in India. May 26 to 27 (sundown to sundown) is Shavuot, a Jewish holiday that has double significance. It marks the wheat harvest in Israel and commemorates the anniversary of the day when the Jews received the Torah at Mount Sinai. May 28 is Pentecost, a Christian holiday which takes place on the 50th day after Easter Sunday; it commemorates the descent of the Holy Spirit upon the Apostles and other followers of Jesus Christ while they were in Jerusalem celebrating the Feast of Weeks, as described in the Acts of the Apostles. May 29 is  Ascension of Bahá’u’lláh, commemorating the ascension of Bahá’u’lláh, the founder of the Bahá’í faith. May 29 is Memorial Day, a federal holiday established to honor military veterans who died in wars fought by U.S. forces.