number skills/concepts mean the skills and concepts that must be gained before number acquisition. We can get those prerequisite skills from the theory of Piaget's Cognitive Development; correspondence, classification, comparison and seriation. These skills, which are essential for all children, take a much larger place in the lives of children with special needs who have difficulty in understanding abstract concepts. The aim of this review study is to give information on the concepts of correspondence, classification, comparison, and seriation studied before the acquisition of the number concept and investigate the research on the concepts and skills before number acquisition in children with special needs. This review study was conducted with 22 studies, which met the inclusive criteria. The studies were examined in terms of skills, design, and interventions. Results showed that classification and seriation were the most studied skills in the studies and effective practices were used in teaching early number skills or concepts. These effective practices were explained and implications for future research were discussed.