The purpose of this study was: 1) to evaluate the effectiveness of a training program in increasing participant creativity using several assessments of creativity; 2) to examine changes in creativity after the training for individual participants; and 3) to investigate possible reasons of a decrease in creativity for some participants after the training. Two theories were used to develop a framework for this study: growth mindset theory (Dweck, 2006) and Vygotsky’s cultural-historical theory (Moran & John-Steiner, 2003).