- 4 April 1930 - Foundation of the American Rocket Society, originally named the American Interplanetary Society
- 13 April 1564 - Pope Pius IV approved the Society of the Holy Name
- 19 April 1866 - First anti-cruelty law was passed since the founding of the American Society for the Prevention of Cruelty to Animals (Brooklyn chapter pictured)
- 22 April 2008 - IEEE Power Engineering Society changed its name to IEEE Power & Energy Society