The development and validation of a scale to assess English-as-a-Second-Language (ESL) learners' perceived self-efficacy are described. Self-efficacy expectations are beliefs about one's ability to perform a given task successfully. Research on self-efficacy and related concepts is reviewed, noting their significant role in predictor human performance. Additionally, research on attitudes and ESL language and literacy learning is examined. A pilot study on development of a self-efficacy scale is summarized, and a more detailed description of efforts to establish reliability and validity of the scale, after modification, is presented. The pilot study was conducted using a 36-item scale with 45 ESL undergraduate students in the United States. The refined 30-item scale was administered to 225 intermediate-level ESL reading and writing learners at four ESL institutions in three countries. Results indicate that the ESL literacy self-efficacy scale is comprised of four factors: perceived abilities; aspiration/persistence/enjoyment; writing affect; and reading affect. The relationships found between ESL learners' literacy self-efficacy and the measure's sub-factors are discussed, and additional implications for research and teaching are considered. The final version of the questionnaire is appended. (Contains 33 references.) (MSE)