The purpose of this study was to evaluate the effects of an 18-day summer tutoring program in which graduate student tutors delivered 15 minutes of differentiated reading instruction (DRI) and a 30-minute interactive read-aloud (IRA) lesson each day. Students in grades K-5 (N = 179) attending a summer program at one urban elementary school completed a lesson-specific combination of pretest and posttest measures of letter-sound knowledge, decoding skills, oral reading fluency, and academic reading attitudes. Students were assigned to groups targeting phonemic awareness and word recognition (PAWR), word recognition and fluency (WRAF), fluency and comprehension (FAC), or vocabulary and comprehension (VAC) based on skill profiles. Paired-samples statistical tests were used to analyze pretest and posttest measures, and tutors were observed with a checklist to document implementation fidelity. Results indicated significant gains on specific subskill mastery measures of letter-sound knowledge for students in PAWR groups and decoding skills for students in PAWR and WRAF groups. Results were not significant for a curriculum-based measure of oral reading fluency for students in FAC groups and were significantly negative for students in VAC groups. There were no significant differences in gains based on instructional group size. There was no evidence of summer learning loss on academic reading attitudes. Tutors were able to implement DRI and IRA lessons with acceptable fidelity. These findings suggest that a summer tutoring program delivered by graduate students can improve targeted reading skills without negatively impacting reading attitudes.