The present study was conducted with the aim of comparing the effectiveness of mindfulness training and compassion therapy on defense mechanisms in socially disadvantaged girls. The statistical population of this research includes all socially disadvantaged teenage girls in health homes under the supervision of the welfare organization of North Khorasan province - Bojnord city - in the second half of 2021. The questionnaire of defense styles of Andrews and colleagues (1993) was used to collect data. This research is a semi-experimental type with a pre-test and post-test 
design with a control group in which 45 people were randomly selected as a sample and randomly divided into two experimental groups and a control group (15 people in each group). One week after the pre-test for all three 
groups, one experimental group was exposed to the independent variable of mindfulness training, and the second experimental group was exposed to compassion therapy training, and the control group did not receive any 
training; Then a post-test was taken from all groups. In this research, in order to investigate the differences between groups, the analysis of variance of the repeated measurement of multivariable factors was used, considering the factor within the group (test) and between the group (group membership). The results showed that mindfulness training and compassion therapy are effective on defense mechanisms in socially disadvantaged girls. Also, another result showed that there is no significant difference between the effectiveness of mindfulness training and compassion therapy on defense mechanisms. Based on the findings of the study, mindfulness training and compassion therapy have been effective in improving the defense mechanisms of socially damaged girls.