Efficacy of an intensive reading intervention implemented during the nonacademic summer was evaluated in children with reading disabilities or difficulties (RD). Students (ages 6–9) were randomly assigned to receive Lindamood-Bell’s Seeing Stars program (n = 23) as an intervention or to a waiting-list control group (n = 24). Analysis of pre- and posttesting revealed significant interactions in favor of the intervention group for untimed word and pseudoword reading, timed pseudoword reading, oral reading fluency, and symbol imagery. The interactions mostly reflected (a) significant declines in the nonintervention group from pre- to posttesting, and (2) no decline in the intervention group. The current study offers direct evidence for widening differences in reading abilities between students with RD who do and do not receive intensive summer reading instruction. Intervention implications for RD children are discussed, especially in relation to the relevance of summer intervention to prevent further decline in struggling early readers.