Despite being a critical emergent literacy skill and an indicator of risk for later reading difficulties, relatively little is known about how alphabet knowledge develops over time. This study utilized a person-centered approach and longitudinal sample of 998 preschool-aged children (M = 56.50 months old) to examine patterns in letter name and letter-sound knowledge development, associations with child, home/family, and classroom factors, and kindergarten readiness outcomes. Results indicated three profiles: children demonstrating initially "High" knowledge and little growth before mastery, children demonstrating initially low knowledge but "Growing" trajectories toward mastery, and children demonstrating initially low knowledge whose growth was substantially "Delayed." Multiple factors distinguished the "High" profile but few distinguished the "Growing" versus "Delayed" profiles; all differed in kindergarten readiness. Implications concerning risk, resiliency, and assessment/instruction are discussed.