To compare the efficacy of instructional programs for adult learners with basic reading skills below the 7th-grade level, 300 adults were randomly assigned to 1 of 3 supplementary tutoring programs designed to strengthen decoding and fluency skills, and gains were examined for the 148 adult students who completed the program. The 3 intervention programs were based on or adapted from instructional programs that have been shown to benefit children with reading levels similar to those of the adult sample. Each program varied in its relative emphasis on basic decoding versus reading fluency instruction. A repeated measures multivariate analysis of variance confirmed small to moderate reading gains from pre- to posttesting across a battery of targeted reading measures but no significant relative differences across interventions. An additional 152 participants who failed to complete the intervention differed initially from those who persisted. Implications for future research and adult literacy instruction are discussed. (Contains 2 tables.)