Background: This study presents the findings of the first administration of a revised "Teachers' Sense of Efficacy for Literacy Instruction" ("TSELI") scale that reflects the changing landscape of 21st-century literacy instruction. Items include such aspects as reading, writing, viewing, listening, communicating using visual, audible and digital materials, vocabulary, comprehension strategies, motivation, differentiated instruction, assessment, diversity culturally responsive teaching and professional literacy learning and leadership. Methods: The survey was reviewed by a panel of seven experts in the field of reading and literacy instruction for content, construct and face validity and then field tested with 12 graduate students to assess the clarity of item wording and instructions, appropriateness of the response scale and ease of administration. The survey was then administered to 476 teacher candidates in two countries. Results: The survey demonstrated moderate inter-rater reliability (0.62) and very high internal reliability (0.95). The 42 items were factor analysed, which demonstrated construct validity and provided an eight-factor scale. Teacher candidates reported having higher self-efficacy regarding 21st-century competencies and lower self-efficacy in early literacy skills. Conclusions: The findings revealed in this paper underscore the importance of measuring pre-service and in-service teacher efficacy for literacy instruction as it relates to contemporary 21st-century literacies, given that the methods and tools addressed in the "Teachers' Self-Efficacy Beliefs for Literacy Instruction in the 21st Century" ("TBLI21c") scale are not reflected in previous literacy self-efficacy instruments, such as reading, writing, viewing, listening, communicating using visual, audible and digital materials, comprehension strategies, motivation, differentiated instruction, diversity, assessment and professional literacy learning and leadership. Results suggest that the "TBLI21c" scale could be a reliable and useful tool to measure in-service and pre-service teacher efficacy for literacy instruction in the 21st century.