IfNotNow is an American Jewish activist group that opposes the Israeli occupation of the West Bank and Gaza Strip. Its membership demonstrates against politicians, United States policies, and institutions that support Israel's occupation, usually seeking to apply pressure through direct action and media appearances. It has been characterized variously as progressive, left-wing, anti-Zionist, or non-Zionist.

IfNotNow's first public action, then under the name "If Not Now, When?" was in July 2014 to protest the Conference of Presidents of Major American Jewish Organizations's support for Israel during the 2014 Israel–Gaza conflict. Activists recited the Jewish prayer of mourning, the Mourner's Kaddish, for all Palestinian and Israeli victims of the war outside the Conferences' office.

The name IfNotNow is derived from a saying of the 1st-century BCE and early 1st-century CE Jewish sage Rabbi Hillel the Elder recorded in Pirkei Avot 1:14: "If I am not for myself, who will be for me? If I am only for myself, what am I? And if not now, when?"

The organization has been variously characterized as progressive or left-wing. The group opposes the Israeli occupation of the West Bank and Gaza Strip, and has been variously described as anti-Zionist or non-Zionist. During a 2025 webinar hosted by IfNotNow, guest speaker Mahmoud Khalil characterized IfNotNow as an "anti-Zionist Jewish space." There were no reports of the group objecting to the characterization. Nonetheless, IfNotNow is generally considered more moderate than Jewish Voice for Peace, which openly characterizes itself as anti-Zionist and supports a boycott of Israel.

Going beyond critiquing the actions of Israel, IfNotNow proposes a Jewish diasporic cultural identity that Professor David Graizbord of the University of Arizona characterized as "left-progressive pan-Judaism." IfNotNow rejects liberal Zionist, centrist, and religious Zionist readings of Jewish history and tradition by characterizing them as artefacts of an out-of-touch American Jewish establishment. IfNotNow is largely agnostic to the desirability of Israel's existence, converging upon the idea that true Jewishness is internationalist and progressive.

IfNotNow is a movement-based organization, designed to appeal directly to the public through social media and direct action; their refusal to participate in closed-door meetings has been criticized by leaders of established Jewish institutions. The IfNotNow movement consists of Jewish Americans, typically millennials, who demonstrate against politicians, U.S. government policies, and Jewish institutions perceived to support the occupation, primarily through direct action and media appearances.

IfNotNow has sought to highlight similarities and ties between the Trump administration and the administration of Israeli Prime Minister Benjamin Netanyahu.

In 2016, the Jewish Federation of Los Angeles, which manages over $1 billion in charitable funds, refused to disburse donor money to IfNotNow.