This paper evaluates a randomized remote tutoring program implemented in Paraguay, targeting 1,650 students in grades four through six with low baseline performance in Spanish language. The intervention provided two weekly 30-minute one-on-one tutoring sessions over the phone for eight weeks, using a differentiated instruction model tailored to students initial diagnostic assessments. Treated students showed significant learning gains: those offered tutoring scored 0.11 standard deviations higher on standardized language tests compared to controls. Effects were consistent across sociodemographic subgroups and baseline achievement levels. Leveraging the random assignment of students to tutors, we estimate individual tutor value added, and find that tutor effects account for 15% of the variation in student outcomes. Tutors in the top quintile have an average value added of 0.38 standard deviations, almost four times the overall effect of the program, underscoring the importance of individual tutor effectiveness in scaling tutoring interventions successfully.