Traumatic events may lead to post-traumatic growth (PTG). Nevertheless, little is known about the mechanisms leading to PTG, especially among older adults. This study sought to examine the direct relationship between world assumptions and PTG and the indirect relationship between them via two possible mediation pathways: post-traumatic stress symptoms (PTSS) and meaning in life. One hundred fifty-nine Holocaust survivors participated in the study (mean age = 82.34, SD = 5.81). Participants completed questionnaires of world assumptions, meaning in life, PTSS and PTG. The findings showed that world assumptions were positive and were positively associated with meaning in life and PTG and negatively associated with PTSS. The results of the multiple mediation model suggest that meaning in life and PTSS partially mediated the relations between world assumptions and PTG. Positive world assumptions were associated with higher meaning in life, which was associated with higher PTG. In contrast, despite the direct association between PTSS and PTG, the mediating effect of PTSS was negative, thus the more positive the world assumptions, the higher the PTG mediated by lower PTSS. The results suggest that the relationship between world assumptions and PTG may be direct and indirect. These findings suggest possible mechanisms underlying PTG, especially in old age. © 2020 John Wiley & Sons Ltd.