Book excerpt: The current practice of having children begin school within a twelve-month cohort is unfair but can be ameliorated by incorporating a dual-entry system. Such a reform effort will dramatically reduce failure, improve student achievement at all levels, while reducing expenditures. Many students are penalized from maximizing their academic potential simply by being born at the wrong time of the year. Not only is there a significant decline in achievement for students born in the second half of the year but they also experience higher rates of failure which negatively impacts self-esteem and reduces future success. Meanwhile, more capable students experience unfairness because of the school’s extraordinary effort at helping their failing students. With so much focus on the weak, many strong students are held back from achieving their potential. Parents agonize over when to begin their child's formal education but lack data for making informed decisions. Educators understand the issue intuitively but decision makers lack data for justifying reform. These informational needs are now available.