Education has been identified as one of the most important ways to achieve national development. With 3 million non-literate adults in Lagos State, the commercial nerve center of the nation, radio becomes a veritable medium to teach such adults who, for several reasons including economic, do not have the opportunity of formal schooling. The study assessed the effectiveness of educational radio broadcasting for adult literacy in Lagos State, Nigeria. Five hundred and five (505) adult learners participating in Lagos is Learning Project were purposively selected. Findings showed that a majority (62.4%) of the study participants used the instructional radio program, "Mooko Mooka," to prepare for classroom instruction, while 53.5% of the study participants used the program for revision. Findings also revealed that 40.6% of them listened to the program three times per week and this implied that frequency of exposure could influence literacy skill. The study concluded that radio instructional techniques were effective in promoting adult literacy and therefore recommended that the radio listening sessions should be increased as part of efforts to reduce adult illiteracy in the country. Also, community media centers should be created in different communities to encourage group listening where learners can be supervised.