To obtain a fuller picture of the efficacy of reading instruction programs for adult literacy learners, gains by individual students were examined in a sample (n = 148) in which weak to moderate gains at the group level had been obtained in response to tutoring interventions that focused on strengthening basic decoding and fluency skills of low literate adults (Sabatini, Shore, Holtzman, & Scarborough, 2011). Learners were randomly assigned to receive one of three tutoring programs for an average of 44 h of instruction. We used within-individual gains replicated over tests (WIGROT) as the method for identifying gainers, who were defined as students whose reading levels increased from pretest to posttest by a half year or more on at least two of four measured aspects of reading proficiency. The 46 % of the sample who met the criterion had higher pretest scores than non-gainers on measures of reading (d = 0.42, p less than 0.01) and phonological awareness (d = 0.47, p less than 0.01), and included fewer adults with a history of special education (43 vs. 61 %, phi = 0.19, p less than 0.05), regardless of which instructional condition had been received. The findings suggest that basic skills instruction can lead to a meaningful degree of benefit for many adult learners who persist in reading programs for several months. Supplementing group level results with analyses of individual growth, such as WIGROT, appears to be useful in evaluating the efficacy of literacy interventions.