This Forum explores nineteenth-century American theater and performance by putting pressure on each of the descriptive terms used—"nineteenth-century," "American," "theater," and "performance." The contributors to this Forum probe how these terms have come to prescribe the kinds of critical work that scholars engage in to talk about theater in the nineteenth century, even as they use the opportunity of the Forum to recover the heterogeneous and subversive ideas that lie behind, or beneath, or around these terms as well. Exploring "nineteenth-century" reveals the alternative temporalities that exist in Native American, Jewish, and African American performance. The idea of "American" becomes a spur for discussing the ways that blackface works in the nineteenth century to equate the notion of Americanness with whiteness. Dissecting the term "theater" reveals the myriad ephemeral but subversive theatrical experiences that interrogated more popular stage productions. Finally, exploring "performance" reveals the way that nineteenth-century performative gestures get performed and recalibrated in today's culture more generally. In this way, this Forum begins to highlight the richness of nineteenth-century American theater and performance by discovering this understudied medium drama as a provocative, even dangerous, engine for studying the long nineteenth century.