1st » Memorial of Saint Joseph the Worker (Roman Catholic optional feast)
1st » Saint Marcouf or Marcouf
1st » Saint Philip the Apostle
1st » Saint Sigismund of Burgundy
1st » Saint Walpurga or Walpurga (canonization)
1st » May 1 (Eastern Orthodox liturgics)
1st » Constitution Day (Latvia)
1st » Constitution Day (Marshall Islands)
1st » Commemoration of the states of Maharashtra and Gujarat following the foundation of Samyukta Maharashtra Samiti (India):
1st » Public holidays in India Secular holidays or Gujarat Day
1st » Maharashtra Day
1st » Earliest day on which National Day of Prayer can fall, while May 7 is the latest; celebrated on the first Thursday in May. (United States)
1st » Earliest day on which World Asthma Day can fall, while May 7 is the latest; celebrated on the first Tuesday in May. (International observance called International)
1st » Festival in honor of Bona Dea (Roman Empire)
1st » International Sunflower Guerrilla Gardening Day (Guerrilla gardening called guerilla gardeners)
1st » EuroMayDay (Western Europe)
1st » Law Day (United States), formerly intended to counterbalance the celebration of Labour Day. (United States)
1st » Loyalty Day, formerly intended to counterbalance the celebration of Labour Day. (United States)
1st » Lei (garland) called Lei Day (Hawaii)
1st » May Day (beginning of Summer) observances in the Northern hemisphere '(see April 30)':
1st » Beltane (Ireland, Scotland, Isle of Man, Celtic neopaganism known as Celtic neopagans and Wiccans in the Northern hemisphere)
1st » Earliest day on which Beltane can fall, while May 7 is the latest; celebrated on the first Monday in May. (Ireland, Scotland)
8th » Michael (archangel) Apparitions of Saint Michael the Archangel or Apparition of Saint Michael
8th » Arsenius the Great (Eastern Orthodox Church)
8th » Desideratus
8th » Catherine de Saint-Augustin
8th » Julian of Norwich (Anglican, Lutheran)
8th » Peter of Tarentaise
8th » May 8 (Eastern Orthodox liturgics)
8th » Earliest day on which Public holidays in Belarus known as State Flag and State Emblem Day can fall, while May 14 is the latest; celebrated on the second Sunday of May. (Belarus)
8th » Earliest day on which World Fair Trade Day can fall, while May 14 is the latest; celebrated on the second Sunday of May. (International observance e.g International)
8th » Time of Remembrance and Reconciliation for Those Who Lost Their Lives during the Second World War, continues to May 9 (International observance called International)
8th » Truman Day (Missouri)
8th » Victory in Europe Day (Europe)
8th » White Lotus Day (Theosophy)
9th » Scientology holidays called Anniversary of Dianetics (Church of Scientology)
9th » Christian Feast Day
9th » Beatus of Lungern
9th » Bienheuré known as Beatus of Vendome
9th » Saint Christopher named Christopher (Αγιος Χριστόφορος) (Eastern Orthodox Church)
9th » George Preca
9th » Gerontius of Cervia
9th » Gregory of Nazianzus, Doctor, Bishop of Constantinople, 389 CE (commemoration, Episcopal Church (USA))
9th » Nicolaus Zinzendorf (Lutheran)
9th » Pachomius
9th » Tudy of Landevennec
9th » May 9 (Eastern Orthodox liturgics)
9th » Europe Day, commemorating the Schuman Declaration. (European Union)
9th » Independence Day, celebrating the declaration of independence of Romania from the Ottoman Empire in 1877. (Romania)
9th » Liberation Day, commemorating the end of the German Occupation of the Channel Islands during World War II). (Guernsey, Liberation Day (Jersey) named Liberation Day (Jersey))
9th » One of the three days of the Feast of the Lemures. (Roman Empire)
9th » Victory Day (9 May) Victory Day observances, celebration of the Soviet Union victory over Nazi Germany (Public holidays in the Soviet Union Soviet Union, Public holidays in Azerbaijan Azerbaijan, Public holidays in Belarus Belarus, Public holidays in Bosn
14th » Matthias the Apostle (Roman Catholic Church)
14th » Michael Garicoïts
14th » Mo Chutu of Lismore (Roman Catholic Church)
14th » Victor and Corona
14th » May 14 (Eastern Orthodox liturgics)
14th » Earliest day on which the first day of Sanja Matsuri can fall, while May 20 is the latest; celebrated on the third weekend of May. (Sensō-ji, Tokyo)
14th » Public holidays in Liberia e.g National Unification Day (Liberia)
15th » Athanasius of Alexandria (Coptic Orthodox Church of Alexandria or Coptic Church)
15th » Dymphna
15th » Hallvard Vebjørnsson (Norway)
15th » Hilary of Galeata
15th » Isidore the Laborer, celebrated with festivals in various countries, the beginning of bullfighting season in Madrid.
15th » Jean-Baptiste de La Salle (Roman Catholic Church)
15th » Peter, Andrew, Paul, and Denise (Roman Catholic Church)
15th » Reticius (Roman Catholic Church)
15th » Sophia of Rome (Roman Catholic church)
15th » May 15 (Eastern Orthodox liturgics)
15th » Republic Day or Constituent Assembly Day (Lithuania)
15th » Earliest date on which Armed Forces Day can fall, while May 21 is the latest; celebrated on the third Saturday of May. (United States)
15th » Earliest date on which Bike-to-Work Day can fall, while May 21 is the latest; celebrated on the third Friday of May. (United States)
15th » Independence Day, celebrates the independence of Paraguay from Spain in 1811. Celebrations for the anniversary of the independence begin on Flag Day, May 14.
15th » International Day of Families (International observance e.g International)
15th » Saint Ubaldo Day named La Corsa dei Ceri begins on the eve of the feast day of Ubald named Saint Ubaldo. (Gubbio)
15th » Mercuralia, in honour of Mercury (mythology) known as Mercury. (Roman Empire)
15th » Nakba Day (Palestinian people e.g Palestinian communities)
15th » Peace Officers Memorial Day (United States)
15th » Armed Forces Day Slovenia called Slovenian Army Day (Slovenia)
16th » Aaron (Copt) e.g Aaron (Coptic Orthodox Church of Alexandria called Coptic Church)
16th » Abda and Abdjesus, and companions:
16th » Abdas of Susa
16th » Andrew Bobola
16th » Brendan named Brendan the Navigator (Roman Catholic Church)
16th » Caroline Chisholm (Church of England)
16th » Saint Germerius known as Germerius
16th » Honoratus of Amiens
16th » John of Nepomuk
16th » Margaret of Cortona
16th » Peregrine of Auxerre
16th » Simon Stock
16th » Ubald (see Saint Ubaldo Day)
16th » Christianity in Sudan known as Martyrs of Sudan (Episcopal Church (USA))
16th » Mass graves in Iraq named Mass Graves Day (Iraq)
16th » National Day, declared by Salva Kiir Mayardit (South Sudan)
17th » Public holidays in Malaysia or Birthday of the Raja (Perlis)
17th » Christian feast day:
17th » Paschal Baylon
17th » William Hobart Hare (Episcopal Church (USA))
17th » Restituta
17th » May 17 (Eastern Orthodox liturgics)
17th » Constitution Day (Nauru)
17th » Norwegian Constitution Day called Constitution Day (Norway)
17th » Earliest date on which Trinity Sunday can fall, while June 20 is the latest; celebrated on the first Sunday after Pentecost. (Western Christianity)
17th » Galician Literature Day or 'Día das Letras Galegas' (Galicia (Spain) known as Galicia)
17th » International Day Against Homophobia and Transphobia aka IDAHO
17th » Liberation Day (Democratic Republic of the Congo)
17th » Great Famine (Ireland) e.g National Famine Memorial Day (Ireland)
17th » Navy Day Argentina or Navy Day (Argentina)
18th » Battle of Las Piedras known as Battle of Las Piedras Day (Uruguay)
18th » Christian feast day:
18th » Ælfgifu of Shaftesbury
18th » Eric IX of Sweden
18th » Felix of Cantalice
18th » Pope John I
18th » Venantius of Camerino
18th » May 18 (Eastern Orthodox liturgics)
18th » Public holidays in Haiti named Flag and Universities Day (Haiti)
18th » History of Somaliland Separatism e.g Independence Day (Somaliland (List of states with limited recognition called unrecognized))
18th » International Museum Day (International observance e.g International)
18th » Mullivaikkal Remembrance Day (Sri Lankan Tamil people or Sri Lankan Tamils)
18th » Public holidays in Turkmenistan known as Revival, Unity, and Poetry of Magtymguly Day (Turkmenistan)
18th » World AIDS Vaccine Day (International observance known as International)
19th » Commemoration of Atatürk, Youth and Sports Day (Turkey, Northern Cyprus)
19th » Greek genocide Political known as Greek Genocide Remembrance Day (Greece)
20th » Christian Calendar of saints known as Feast Day:
20th » Abercius and Helena
20th » Aurea of Ostia
20th » Austregisilus
20th » Baudilus
20th » Bernardino of Siena
20th » Ivo of Chartres
20th » Lucifer of Cagliari
20th » Saint Sanctan known as Sanctan
20th » May 20 (Eastern Orthodox liturgics)
20th » The first First Council of Nicaea or Council of Nicaea, CE 325 (commemoration, Anglicanism)
20th » Day of Remembrance (Cambodia)
20th » Emancipation Day Florida or Emancipation Day (Florida)
20th » European Maritime Day (European Council)
20th » Independence Day, celebrates the independence of Cuba from the United States in 1902.
20th » Independence Day, celebrates the independence of East Timor from Indonesia in 2002.
20th » Indonesian National Awakening (Indonesia)
20th » Josephine Baker Day - in 1951 the National Association for the Advancement of Colored People (NAACP) named May 20 Josephine Baker Day in honor of her efforts and fight against racism.
20th » National Day (Cameroon) or National Day (Cameroon)
21st » Constantine the Great and Christianity e.g Emperor Constantine I
21st » Earliest day on which Corpus Christi (feast) known as Corpus Christi can fall, while June 24 is the latest; held on Thursday after Trinity Sunday. (Roman Catholic Church)
21st » Helena of Constantinople, also known as "Feast of the Holy Great Sovereigns Constantine and Helen, Equal-to-the-Apostles." (Eastern Orthodox Church)
21st » May 21 (Eastern Orthodox liturgics)
21st » Circassian Day of Mourning (Circassians)
21st » Armed Forces Day Hungary or Day of Patriots and Military (Hungary)
21st » Navy Day (Chile)
21st » Saint Helena Day, celebrates the discovery of Saint Helena in 1502.
21st » World Day for Cultural Diversity for Dialogue and Development (International observance or International)
22nd » Abolitionism known as Abolition Day (Martinique)
22nd » Christian Calendar of saints or Feast Day:
22nd » Castus and Emilius
22nd » Saint Fulk known as Fulk
22nd » Saint Humility or Humilita
22nd » Quiteria
22nd » Rita of Cascia
22nd » Romanus of Subiaco
22nd » May 22 (Eastern Orthodox liturgics)
22nd » Harvey Milk Day (California)
22nd » International Day for Biological Diversity (International observance May e.g International)
22nd » United States National Maritime Day known as National Maritime Day (United States)
22nd » Public holidays in Haiti or National Sovereignty Day (Haiti)
22nd » Republic Day (Sri Lanka)
23rd » Christian Calendar of saints e.g Feast Day:
23rd » Julia of Corsica
23rd » Aaron the Illustrious (Syriac Orthodox Church)
23rd » Desiderius of Vienne
23rd » Quintian, Lucius and Julian
23rd » Nicholas Copernicus and Johannes Kepler (Episcopal Church (USA))
23rd » May 23 (Eastern Orthodox liturgics)
23rd » Labour Day Jamaica e.g Labour Day (Jamaica)
23rd » World Turtle Day
24th » Aldersgate Day/John Wesley named Wesley Day (Methodism)
24th » Public holidays in Ecuador known as Battle of Pichincha Day (Ecuador)
24th » Bermuda Day (Bermuda)
24th » Christian Feast Day:
24th » David I of Scotland
24th » Donatian and Rogatian
24th » Jackson Kemper (Episcopal Church (USA) named Calendar of saints (Episcopal Church))
24th » Joanna, wife of Chuza called Joanna
24th » Saint Sarah named Sarah (celebrated by the Romani people of Camargue)
24th » Vincent of Lérins
24th » May 24 (Eastern Orthodox liturgics)
24th » Belize Holidays named Commonwealth Day (Belize)
24th » Earliest day on which Baby jumping named El Colacho tradition can fall, while June 27 is the latest; celebrated on Sunday after Corpus Christi. (Castrillo de Murcia, near Burgos)
24th » Independence Day (Eritrea) known as Independence Day, celebrates the independence of Eritrea from Ethiopia in 1993.
24th » Lubiri e.g Lubiri Memorial Day (Buganda)
24th » Saints Cyril and Methodius Saints Cyril and Methodius Day called Saints Cyril and Methodius Day (Eastern Orthodox Church) and its related observance:
24th » Public holidays in Bulgaria named Bulgarian Education and Culture and Slavonic Literature Day (Bulgaria)
24th » Victoria Day (Canada) called Victoria Day; celebrated on Monday on or before May 24. (Canada), and its related observance:
29th » Pope Alexander of Alexandria (Eastern Orthodox Church)
29th » Theodosia of Constantinople (Eastern Orthodox Church)
29th » May 29 (Eastern Orthodox liturgics)
29th » Democracy Day (Nigeria)
29th » Earliest day on which Feast of the Sacred Heart can fall, while July 2 is the latest; celebrated 19 days after Pentecost. (Catholic Church)
29th » International Day of United Nations Peacekeepers (International observance or International)
29th » Oak Apple Day (England)
30th » Public holidays in Anguilla known as Anguilla Day, commemorates the beginning of the History of Anguilla Recent history e.g Anguillian Revolution in 1967. (Anguilla)
30th » Public holidays in Spain or Canary Islands Day (Canary Islands)
30th » Christian Calendar of saints known as Feast Day:
30th » Earliest day on which Immaculate Heart of Mary Roman Catholic feast days named Feast of the Immaculate Heart of Mary can fall, while July 3 is the latest; celebrated 20 days after Pentecost. (Catholic Church)
30th » Ferdinand III of Castile
30th » Isaac of Dalmatia
30th » Joan of Arc
30th » May 30 (Eastern Orthodox liturgics)
30th » Indian Arrival Day Trinidad and Tobago or Indian Arrival Day (Trinidad and Tobago)