Mathematics is one of the core school subjects in the UK and an emphasis is placed on developing pupils' mathematical competencies throughout all key stages. Despite that, the attainment of students with disabilities in mathematics remains low. The current study explored ways in which the Teaching Early Numeracy to children with Developmental Disabilities (TEN-DD) programme could be implemented by teaching staff in a special school in the UK to improve the numeracy skills of students with autism. Adaptations to the delivery of the programme were made during the study as a result of continued collaboration with the participating school. The findings suggest that it may be feasible to implement the TEN-DD programme using a school staff delivery model and it may help learners improve their early numeracy skills. Practical aspects of TEN-DD's implementation highlighted the need to incorporate more systematic adaptations for minimally verbal students, as well as for learners who might need additional training with prerequisite skills.