Mass psychogenic response (MPR), also referred to as epidemic hysteria, mass hysteria, or mass psychological illness, has been identified for over 600 years. MPR is a syndrome comprising a collection of symptoms, which are consistent with organic illness, but lack an identifiable cause, and which rapidly spread through socially connected groups due to psychogenic factors. Symptoms are often described following a perceived or suspected exposure, such as a strange odor, and can be difficult to differentiate from illness stemming from infectious or environmental etiologies. Predominant symptoms found in case reports of MPR include headache, lightheadedness, abdominal pain, cough, hyperventilation, irritated eyes, rash, itching, and weakness, with the majority of reported outbreaks occurring in school settings. This article describes an outbreak of pruritus in an elementary school on March 15, 2006, during the week of Maryland School Assessment (MSA) testing, and the measures taken by the school and health personnel. This outbreak of pruritus highlights multiple characteristics of MPR: (1) the symptoms were benign and transient; (2) environmental and medical evaluations did not reveal a likely etiology; (3) the students were under psychological stress due to standardized testing; (4) there was line of sight transmission; (5) although the students reported severe itching, the only visible sign was erythema consistent with scratching; (6) the number of students with itching escalated with increasing media coverage; (7) females were affected more than males; (8) itching spread from the fifth graders to the younger students; and (9) symptoms began rapidly, spread explosively, and, after reassurance and return to routine, rapidly abated. While biological and environmental causes must always be considered and evaluated, maintaining a suspicion for MPR in school settings may prevent unnecessary social disruption, anxiety, resource expenditure, and invasive medical interventions. Measures such as those taken by the school and health personnel in this outbreak may be helpful in similar situations. (Contains 2 figures.)