The International Day of Happiness is celebrated throughout the world on the 20th of March. It was established by the United Nations General Assembly on 28 June 2012.
Assembly Resolution A/RES/66/281 states in pertinent part:
• The purpose of the Day of Happiness Project  is to unite happy people of all nationalities and religions under the umbrella of the non-religious moral code outlined in The Way to Happiness booklet which includes 21 precepts like TAKE CARE OF YOURSELF, LOVE AND HELP CHILDREN, SET A GOOD EXAMPLE, DO NOT HARM A PERSON OF GOOD WILL, SAFEGUARD AND IMPROVE YOUR ENVIRONMENT, TRY TO TREAT OTHERS AS YOU WOULD WANT THEM TO TREAT YOU and many others that will help you live a happy life. The Day of Happiness Project was founded to support the United Nations International Day of Happiness, which occurs March 20 of every year starting in 2013.
The General Assembly, Conscious that the pursuit of happiness is a fundamental human goal,Recognizing also the need for a more inclusive, equitable and balanced approach to economic growth that promotes sustainable development, poverty eradication, happiness and the well-being of all peoples, Decides to proclaim 20 March the International Day of Happiness, Invites all Member States, organizations of the United Nations system and other international and regional organizations, as well as civil society, including non-governmental organizations and individuals, to observe the International Day of Happiness in an appropriate manner, including through education and public awareness-raising activities
— United Nations General Assembly, Resolution adopted by the General Assembly on 28 June 2012