Purpose: The purpose of this study was to identify the influence of hope, core beliefs, and social support on the posttraumatic growth of mothers with chronically ill children. Methods: In this study, 94 mothers who gave written consent completed the questionnaires between July 21 and July 31, 2012 when they visited a university hospital in Seoul, Korea. Data were analyzed using t-test, ANOVA, Pearson correlation coefficient and stepwise multiple regression. Results: Hope, core belief and social support had positive correlations with posttraumatic growth. Models including these variables explained 64.8% (F=55.276, p<.001) of the variance for posttraumatic growth. Hope (${eta}$=.441, p<.001) was the most influential factor. Conclusion: The findings demonstrate that it is essential for nurses to mediate and facilitate posttraumatic growth of mothers caring for chronically ill children. Furthermore, there is an need to develop and implement new strategies in clinical practice that will result in improvements in posttraumatic growth.