| Lei
Day - 1 |
| May
Day - 1 |
| National
Law Day - 1 |
| National
Executive Cooking Day - 1 |
| National
Loyalty Day - 1 |
| National
Mother Goose Day - 1 |
| Save
the Rhino Day - 1 |
| School
Principal's Day - 1 |
| National
Teen Day - 1 |
| National
Anxiety Disorders Screening Day - 2 |
| Roberts
Rules of Order Day - 2 |
| Sibling
Appreciation Day - 2 |
| Library
Legislative Day - 2 |
| National
Lumpy Rug Day - 2 |
| National
Tax Freedom Day - 2 |
Tax
Freedom Day - 3
 |
| United
Nations World Press Freedom Day - 3
|
| International
Tuba Day - 4 |
| National
Weather Observer's Day - 4 |
| National
Relationship Renewal Day - 4 |
| Bonza
Bottler Day TM - (5/5) |
| Cinco
de Mayo - 5 |
| National
Cartoonist Day - 5 |
|
National Day of Prayer -
5
(First Thursday in May)
|
| National
Indian Day - 5 |
| Totally
Chipotle Day - 5 |
| International
UNmothers Day - 6 |
| National
Nurses Day - 6
|
| National
No Diet Day - 6 |
| National
Anniversary of the first Postage Stamp - 6 |
| National
Melanoma Monday Day - 7 |
| National
Teacher Day - 7 |
| National
World Red Cross Day - 7 |
|
Mother's Day - 8 |
|
No Socks Day - 8 |
| V-E
Day - May 8, 1945 |
| World
Red Cross Day - 8 |
| National
Night Shift Workers Day - 9 |
| National
Third Shift Workers Day - 9 |
| National
Receptionists Day - 10 |
| National
Small Business Day - 10 |
| National
Read-in Day - 10 |
| Eat
What You Want Day - 11 |
| Trust
Your Intuition Day - 11 |
| International
Migratory Bird Day - 12 |
| National
Limerick Day - 12 |
| National
Kite Day - 13 |
| Mother
Ocean Day - 13 |
| Underground
America Day - 14 |
| International
Day of Families - 15 |
| National
Employee Health & Fitness Day - 15 |
| National
Hug Your Cat Day - 15 |
| Peace
Officer Memorial Day - 15 |
| True
Confessions Day - 15 |
| National
Biographers Day - 16 |
| National
"Be a Millionaire" Day - 16 |
| National
Employee Health and Fitness Day - 16 |
| National
Bike to Work Day - 16 |
| New
York Stock Exchange Anniversary - 17 |
| United
Nations World Telecommunication Day - 17
|
| International
Museum Day - 18
|
| National
Visit Your Relatives Day - 18 |
| National
Do Dah Day - 19 |
| United
Nations World Refugee Day - 20
|
| American
Red Cross Founding Day (1881) - 21 |
|
Armed Forces Day - 21 (Third Saturday in May) |
| National
Wait Staff Day - 21 |
| National
Maritime Day - 22 |
| United
Nations International Day for Biological
Diversity - 22
|
| National
Turtle Day - 23 |
| National
Mudbug Madness Day - 24 |
| National
Missing Children's Day - 25 |
| National
Tap Dance Day - 25 |
|
National Grape Popsicle Day - 27 |
| National
Jazz Days - 27 |
| National
Ancestor Honor Day - 27 |
| United
Nations World
No-Tobacco Day - 28
|
| National
Loomis (Telegraphy) Day - 30 |
| Memorial
Day - 30
(officially observed last Monday in May) |
| National
No Tobacco Day - 31 |
