This study reports findings of a systematic replication and as such sought to evaluate effects of an early numeracy curriculum on early number sense attainment for Kindergarten students with autism. Through daily 15-min story-based math lessons with embedded systematic instruction delivered by their classroom teacher, participants learned to compare sets, identify and work with patterns, and use standard and nonstandard measurement, and calendar skills. Results indicate a functional relation between the intervention and early number sense, and students were able to generalize skills when systematic instruction was faded. Similar results were mirrored by pre-post standardized norm-referenced measures of early mathematics abilities. Implementation of the curriculum had positive results on the teacher's perception of self-efficacy. The study's contribution to research, recommendations for practice, and implications for future research are discussed.