This study aimed to develop scales to measure school counselors' (SCs) transitional support behaviors and their related perceptions and examined the factors that influence those behaviors. A questionnaire was administered to 325 elementary, middle, and high school SCs. Using a factor analysis, the “Transitional Support Perception Scale,” comprising fıve factors of 19 items, and the “Transitional Support Behavior Scale,” comprising eight factors of 31 items, were developed. Additionally, to identify the factors influencing transitional support behaviors, a multiple regression analysis was conducted. This analysis used the perception of transitional support, years of SCs experience, clinical experience, and the reason for starting transitional support as dependent variables; transitional support behaviors were used as the control variables. The results showed that the reasons for starting transitional support and clinical experience influenced on transitional support behavior positively. Nonetheless, the influence of transitional support perception was limited. In promoting transitional support behaviors of SCs, it was considered necessary to set up a transitional support system, to systematize effective handover methods, and to improve the skills of SCs involved in coordination and transitional support.