The postwar period brought sweeping changes for American Jews. Communal socioeconomic transitions and the aftermath of the Holocaust triggered intense anxieties among Jewish leaders regarding the preservation of so-called Jewish "authenticity," and to an increased focus on the moulding of American Jewish youth. This article considers how Jewish summer camps used Tisha B'Av and secular, alternative memorial days, to lead campers toward various, ideologically imbued visions of Jewish authenticity. Through fostering an aura of tragedy in what was otherwise a world of play, songs, and enjoyment, Jewish educators used memorial days as transformative educational tools. Though camps' ceremonies looked remarkably similar, often including a carefully crafted sombre atmosphere, dirges, and responsive readings, the message of the days proved malleable to different ideological perspectives. This article considers how Zionist, Yiddishist, Reform and Conservative camps came to use memorial days to produce "real," "ideal," or "authentic" Jews in accordance with their ideological visions in the decades immediately following the Holocaust.