We developed the Humanitarian Emergency Settings Perceived Needs (HESPER) Scale, a valid and reliable scale to rapidly assess perceived needs of populations in humanitarian settings in low- and middle-income countries. We generated items through a literature review; reduced the number of items on the basis of a survey with humanitarian experts; pilot-tested the scale in Gaza, Jordan, Sudan, and the United Kingdom; and field-tested it in Haiti, Jordan, and Nepal. During field-testing, intraclass correlation coefficients (absolute agreement) for the total number of unmet needs were 0.998 in Jordan, 0.986 in Haiti, and 0.995 in Nepal (interrater reliability), and 0.961 in Jordan and 0.773 in Nepal (test-retest reliability). Cohen's κ for the 26 individual HESPER items ranged between 0.66 and 1.0 (interrater reliability) and between 0.07 and 1.0 (test-retest reliability) across sites. Most HESPER items correlated as predicted with related questions of the World Health Organization Quality of Life-100 (WHOQOL-100), and participants found items comprehensive and relevant, suggesting criterion (concurrent) validity and content validity. The HESPER Scale rapidly provides valid and reliable population-based data on perceived needs in humanitarian settings.