Much is known about short-term--but very little about the long-term--effects of reading interventions. To rectify this, a detailed analysis of follow-up effects as a function of intervention, sample, and methodological variables was conducted. A total of 71 intervention-control groups were selected (N = 8,161 at posttest) from studies reporting posttest and follow-up data ([mean] = 11.17 months) for previously established reading interventions. The posttest effect sizes indicated effects ([mean weighted effect sizes] = 0.37) that decreased to follow-up ([mean weighted effect sizes] = 0.22). Overall, comprehension and phonemic awareness interventions showed good maintenance of effect that transferred to nontargeted skills, whereas phonics and fluency interventions, and those for preschool and kindergarten children, tended not to. Several methodological features also related to effect sizes at follow-up, namely experimental design and dosage, and sample attrition, risk status, and gender balance. (author abstract)