A model for educating children in grades pre-kindergarten (PK) through third grade (3) was tested in the current study. The PK-3 Approach includes Structure (e.g., class size, teacher training) Process components (e.g., emotional & instructional classroom climate) in addition to Aligning and Coordinating children\u27s experiences across grades PK-3. Alignment and Coordination is the lining up of standards, curricula, and assessment practices and ongoing efforts to maintain this alignment in the context of the student population. A comparative case study design was implemented in three urban public schools serving low-income student bodies, but with different fourth grade achievement outcomes in literacy and math. The main goals of the study were to: (1) examine empirical evidence regarding the relationship between a PK-3 Approach to education and fourth grade achievement outcomes; and (2) discover variations in PK-3 implementation which could then be used to modify the original model. Data from classroom observations using the CLASS, archival school records, and teacher and principal interviews were collected in order to characterize how each school operates on a daily basis, and then to compare the three school types in the context of the PK-3 Approach. Alignment and Coordination components best discriminated among the three schools, with the highest achieving school implementing within grade (horizontal) and across grade (vertical) Alignment and Coordination activities across subjects on a regular basis. The school with the next highest level of achievement implemented horizontal Alignment and Coordination for the literacy curriculum; and the lowest performing school (average for the population they served) did not implement any level of Alignment and Coordination except for monthly within grade meetings designed for teachers to agree on literacy topics to be taught. Process components discriminated between the two higher performing schools and the lowest performing school; and Structure components were either non-significant, or did not predict achievement in hypothesized directions. Alignment and Coordination moderated the relationship between teacher training (Structure) and Instructional Climate in the classroom (Process), whereby teachers with training above and beyond an M.A. in education was related to higher Instructional Climate scores in the lowest performing school, but no significant relationship was found in the two higher performing schools. Results are discussed in terms of educational policies