Spelling is a key transcription skill for writing. While little is understood about the particular challenges some students experience when learning to spell, explicit instruction is known to improve spelling performance. The study reported in this article draws on eight case studies from a larger Australian mixed-methods study examining spelling acquisition, as represented by a stratified random sample of Australian students aged 8 to 12 years (n=1,198). This case study utilised Triple Word Form Theory for the spelling error analysis of dictated words, narrative and expository writing, as well as semi-structured interview data from a randomly selected sample of low-achieving spellers. Analyses of phonological, orthographic and morphological spelling errors revealed students' common and unique challenges in learning to spell. Qualitative analysis of semi-structured interview data identified that the students lacked confidence in spelling, used limited strategies for spelling unknown words, and displayed constrained metalanguage associated with spelling. Interview data from the respective classroom teachers revealed that the teachers had inadequate strategies for teaching spelling and lacked confidence in their ability to teach spelling. The findings highlight the need for improved ways to support those students beyond the first few years of schooling who find learning to spell challenging.