The purpose of this study was to investigate secondary mathematics teachers' conceptions of the barriers to the development of mathematical literacy. The data were collected through semi-structured interviews with sixteen in-service mathematics teachers from nine secondary schools of five different school types. The data analysis consisted of an inductive analysis process for identifying and labeling the patterns or themes through examining interview data with the help of NVivo qualitative data analysis software. The results indicated that teachers' conceptions regarding the barriers to mathematical literacy development could be categorized under: (i) conceptual challenges (What is mathematical literacy?); (ii) educational challenges (How can we develop mathematical literacy?); and (iii) systemic challenges (Where is mathematical literacy (to be) located?). The teachers' identification of different obstacles to the development of mathematical literacy can account for the fact that each teacher in this study has diverse but convergent conceptions of mathematical literacy. This fact also promises hope for assisting teachers in resolving these obstacles that have been raised from various angles.