Month-long observances:
- ALS Awareness Month
- Haitian Heritage Month
- Indian Heritage Month
- Jewish-American Heritage Month
- Mental Health Month
- National Asian American and South Pacific Islander Heritage Month
- Older Americans Month
- South Asian American Heritage Month
Important D&I calendar dates:
- May 5 – Cinco de Mayo
- May 9 – Laylat al-Qadr (Muslim)
- May 11 – Ramadan ends (Muslim)
- May 12 – Eid al-Fitr (Muslim)
- May 17 – International Day Against Homophobia, Transphobia and Biphobia
- May 21 – World Day for Cultural Diversity for Dialogue and Development
- May 22 – Declaration of the Bab (Baha’i)
- May 29 – Ascension of Baha’u’llah (Baha’i)
- May 31 – Memorial Day