Science and theatre were intertwined from the start of ‘modern drama’ in the works of Georg Buchner and Émile Zola, who ushered modern ideas about science into the theatre and made conscious engagement with science an intrinsic part of a break with the theatrical past. This chapter traces the explicit, conscious interaction between science and the modern stage, from August Strindberg and Henrik Ibsen’s works through to those of Bernard Shaw, Leonid Andreyev, Maxim Gorky, Elizabeth Robins, Eugène Brieux, Harley Granville Barker, Karel Čapek, Tawfiq al-Hakim, James Ene Henshaw, Mary Burrill, Susan Glaspell, and Sophie Treadwell; the probing of race science on stage by Harlem Renaissance playwrights; the Federal Theatre Project’s science-inflected productions; and Bertolt Brecht’s changing depiction of science and scientists. In addition, there is another meaning of ‘science in the theatre’ that the chapter draws out: the hidden, often unacknowledged roles played by science and technology in staging.