This research study focused on the developmental age of children who were entering kindergarten rather than focusing on chronological age or pre-established knowledge criteria. This study utilized a mixed-methods approach to identify an early childhood intervention program that concentrated on the developmental levels of children. State law determines entrance age into kindergarten; however, this set age may not be the best time for all students to begin school. By identifying developmental levels of children, assistance could be given in providing a program that would meet the developmental needs of the students. Another factor formerly utilized to determine whether children were ready for school was the amount of knowledge that they possessed. Knowledge improved readiness for kindergarten, particularly since teachers, parents, and students focused their entire educational evaluation on grades. In the past, a person's intelligence was labeled as the sole measuring device for academic and lifelong success. The theory of developmental age explicates these previous determining factors and provides consideration of a child's developmental age. This study explored whether students who were not developmentally ready for kindergarten benefited from an extra year spent in a developmental program. It also examined the capability of parents and teachers to identify a difference in a child's maturity, behavior, academic achievement, and social development after attending a developmental program. The program that was researched was entitled Kinderstart. It was created by and for a group of kindergarten teachers and their students in order to help address these issues. In the research study surveys, interviews, grades, behavioral analyses, grade-point averages, and class rankings were examined to help determine the success of the school system because of their developmental program. From this study, it was found that the program was successful overall in each of the different realms researched. However, it was also found that this program was not 100% successful for every student. Research that is more extensive would need to be gathered on environmental influences, which may also require a larger sampling.