The aim of the study is to examine the effects of Colorful Worlds of Sounds Program on phonological awareness skills of preschool children. The research design is quasi-experimental pretest-posttest with control group. Study group was chosen from a preschool by random sampling among public preschools located in Eskisehir city center during the 2014-2015 education year of spring semester. In that preschool located in Eskisehir, one of the preschool classroom in which 5 years of age (60-72 months) children were enrolled was assigned as experimental group and another classroom was assigned as control group. There were 24 children in experimental group and 19 children in the control group. "General Demographic Form" and "The Phonological Awareness Scale of Early Childhood Period (PASECP)" were used as measurement tools. After the pretest was applied to children in the experimental and control groups, Colorful Worlds of Sounds Program was implemented to the experimental group children by the researcher. The program implemented throughout eight weeks, three days in a week and an hour in a day. At the end of the implementation, posttest was applied to both the experimental and the control group. 2x2 mixed ANOVA was used to reveal whether there is a significant difference between the pretest and posttest of total phonological awareness scores of the experimental and the control group or not. Moreover, 2x2 mixed ANOVA was used to compare pretest and posttest scores obtained from the subtests. The results indicated that there was a significant difference between total phonological awareness scores of the experimental and the control group and all subtests scores of the groups. Based on these results it can be said that Colorful Worlds of Sounds Program was effective to develop preschool children's phonological awareness skills.