1897 - Paris (France) - Andre Antoine's naturalistic theatre: the rise of the fourth wall.
1898 - Moscow (Russia) - Art Theatre founded by Constantin Stanislavski on the principle of realistic theatre.
1910s - Moscow (Russia) - Film Director Lev Kuleshov demonstrates the Kuleshov effect: "a mental phenomenon by which viewers derive more meaning from the interaction of two sequential shots than from a single shot in isolation".
1920 - Paris (France) - Jacques Copeau introduces mask improvisation at the Ecole du Vieux-Colombier.
1921 - Vienna (Austria) - J.L. Moreno directs the "Theatre of Spontaneity" and develops Psychodrama.
1935 - New York (US) - Sanford Meisner join the Neighborhood Playhouse and starts developing his teaching technique.
1936 - (Germany) - Berthold Brecht introduces the notion of Distancing Effect (Verfremdungseffekt) in an essay first published in a London revue.1939 - Chicago (US) - Viola Spolin starts developing the concept of Theatre Games.
1944 - Northampton (US) - Experimental psychologists Fritz Heider and Marianne Simmel use a simple video animation to study the way audiences compose narratives.
1945 - (England) - Joan Littlewood founds the Theatre Workshop, twice prosecuted for using improvisation in performance.
1951 - Milan (Italy) - Jacques Lecoq creates the Theatre School of the Piccolo Teatro.
1955 - Chicago (US) - David Shepherd and Paul Sills found the Compass Players, later to become The Second City.
1958 - London (England) - Keith Johnstone starts using improvisation to train students at the Royal Court Theatre.
1959 - Opole (Poland) - Jerzy Grotowski founds the Laboratory Theatre.
1963 - (US) - Viola Spolin's Improvisation for the Theater is published.
Late 1960s - San Francisco (US) - Del Close develops the Harold long form of improvisation.
1968 - (Scandinavia) - Jerzy Grotowski publishes Towards a Poor theatre.
1970s - (US) - Action Theater is created by Ruth Zapora, Contact improvisation by Steve Paxton and Viewpoints by Mary Overlie.
1973 - (Latin America) Augusto Boal develops Invisible theatre and later Forum Theatre.
1975 - New York State (US) - Jonathan Fox develops Playback Theatre.
1977 - Quebec (Canada) - Robert Gravel's Ligue Nationale d'Improvisation stages the first public performance mixing improvisation with sport.
1977 - London (England) - Mike Leigh directs Abigail's Party.
1978 - Calgary (Canada) - Keith Johnstone's TheatreSports first public match.
1978 - Ottawa (Canada) - Carleton High School's Improv Olympics is founded.
1979 - (Canada) - Impro: Improvisation and the Theatre by Keith Johnstone is published.
Main source (with several additions): The Novelty of Improvisation: Towards a Genre of Embodied Spontaneity (open access) by David Alfred Charles - PhD Dissertation - Department of Theatre - Louisiana State University, August 2003. All rights reserved.