To study how attitudes and social psychological processes influence decisio
ns about war and peace, a 15-question scale was developed to measure moral
disengagement in support for military action. In a survey of 128 secondary
school students in the USA and Finland, the scale demonstrated acceptable r
eliability (0.85-0.90) in different gender and national groups. US students
were less morally engaged than Finnish students and males were less morall
y engaged than females. Scale scores were strongly related to the students'
support for US and NATO military actions in Iraq and Yugoslavia. In a seco
nd study, 73 US university students participated in a brief, randomized exp
eriment comparing the effects of contrasting communications on moral diseng
agement in support for military action. After completing a pretest survey,
the students were randomly assigned to persuasive communications favoring e
ither moral disengagement or resistance to moral disengagement. Immediately
after they received these communications, the students were given the oppo
rtunity to give new answers to the survey questions about moral disengageme
nt and approval of specific military actions. Analyses of pretest data conf
irmed the reliability of the scale and its ability to predict opinions abou
t the US and NATO bombing campaigns in Iraq and Yugoslavia. Analyses of cha
nge scores showed increasing moral disengagement in one group and decreasin
g moral disengagement in the other group, in accordance with the type of co
mmunication that was provided between surveys. The groups also differed sig
nificantly in their changes of opinions about the NATO bombing of Yugoslavi
a and in their subsequent willingness to sign letters of praise or protest
for their US Representative's congressional vote against the bombing.