School readiness includes a constellation of skills and behaviors, such as social and emotional development, language and literacy, and self-regulation that provide a basis critical for classroom participation and learning. Whereas it has been well-established that students who enter kindergarten with weaknesses in language and literacy are more likely to struggle academically, less research has focused on the variability and educational impact of other foundational learning components, including internalizing and externalizing behaviors, particularly in first grade. This study used latent profile analysis to identify the following four subgroups (profiles) of students, using foundational learning components, in a sample of first graders (n = 324): Emergent Hyperactive, Externalizing, Generally Good Students, and Internalizing. Latent class growth analysis illustrated significant differences in the average rate of growth in literacy skills from the beginning to the end of first grade across the four profiles, after controlling for gender and socioeconomic status. Findings indicated the greatest growth in literacy skills for students in the Externalizing profile and the least amount of vocabulary growth for students in the Emergent Hyperactive profile followed by the Internalizing profile. Educational implications of how researchers and educators might consider students' individual differences across profiles of foundational learning components to inform ways to support development and learning in the classroom are discussed.

Many assume that cognitive and linguistic processes, such as semantic knowledge (SK) and self-regulation (SR), subserve learned skills like reading. However, complex models of interacting and bootstrapping effects of SK, SR, instruction, and reading hypothesize reciprocal effects. Testing this "lattice" model with children (n = 852) followed from first to second grade (5.9-10.4 years of age) revealed reciprocal effects for reading and SR, and reading and SK, but not SR and SK. More effective literacy instruction reduced reading stability over time. Findings elucidate the synergistic and reciprocal effects of learning to read on other important linguistic, self-regulatory, and cognitive processes; the value of using complex models of development to inform intervention design; and how learned skills may influence development during middle childhood.