Events that occurred on 31 March.
 On Earth
- 1979 - J.R.R. Tolkien: Scholar and Storyteller is published.
- 2006 - The Lord of the Rings 1954-2004: Scholarship in Honor of Richard E. Blackwelder is published.
- 2008 - Tolkien's Gedling is published.
- 2008 - Stormfront Studios, developers of the 2002 video game The Lord of the Rings: The Two Towers, ceases trading.
 In Arda
Note: Months of the Shire Calendar only have 30 days, so no events have nor will happen on the 31st.