Development of language is taken for granted by most. Problems with language development can result in stress for the individual and family; there is a challenge in that the contemporary education system assumes children have appropriate skills when they begin school. The purpose of the study is to further test a theoretical model of language readiness known as language-based cognitive fitness, which includes measures associated with structural concepts of language involving verbal reasoning ability, visual synthesis, and active analysis that explained 91% of the variance in achievement, with longitudinal data. The sample includes children from a private school who received an extensive battery of tests at admission and annually thereafter. Scores from 11cognitive measures were used in a structural equation modeling framework to test the model derived from cross-sectional data with longitudinal data over three time points. Results from this longitudinal analysis demonstrated language-based cognitive fitness to be an interaction of verbal reasoning abilities, visual synthesis, and active analysis depending on the time period. There is a hint of hierarchical structure but it is a secondary consideration to the core model. Implications for positive social change include an improved understanding of the language structures responsible for language deficits and how these relate to overall cognitive fitness; and, the potential for interventions crafted to help children more quickly make up language deficits.