The purpose of this study was to examine the most popular educational preschool apps available to consumers to establish their alignment with early literacy learning outcomes and learning science principles. More specifically, this study examined (a) the descriptive characteristics of popular educational apps detailed in the Apple App Store, (b) the extent to which these mobile apps are intended to support the acquisition and growth of early literacy skills for preschool children as defined by national early literacy learning outcomes, (c) the presence of Learning Science principles within app activities, and (d) how app customer ratings align to content.This study used content analysis methods to conduct an organized investigation of the content of the ever-increasing mobile apps intended for children. Data were collected from a sample of young children's mobile apps that were offered in Apple's App Store. This study also sought to explore the degree to which mobile apps intended for the education of young children are designed in accordance with the core principles of the learning sciences. An essential part of this study was an examination of the content of educational apps, particularly those apps that claim to teach early literacy skills. A frequency analysis was used to determine the number and percent of apps supporting each Learning Science pillar and the acquisition and growth of early literacy skills as defined within the Head Start Early Learning Outcomes Framework (HSELOF). The pillars of active learning, meaningful learning, and engaged learning rated high within a majority of the apps. The pillar of social interaction was difficult to find in each app. The literacy apps in this sample had a central focus on alphabet knowledge activities. A log linear analysis was used to determine if the presence of any one Learning Science pillar could predict the presence of other pillars. A connection between active learning and engaged learning was the most significant. Last, app customer ratings were also compared to the HSELOF alignment using a frequency analysis. When examined, the apps rated 4.5 stars and higher, and all were aligned with alphabet knowledge skills. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]