The provision of school based psychological services in Victorian primary and secondary schools dates back to well before the Second World War. Since then, however, the activities that make up the role of school psychologists have changed substantially. School psychologists' roles have become more varied than the original psychometric focus and reflect a more systemic approach to the conceptualization of student problems. Within Australia, school psychologists can be found servicing single or multiple schools in the government, independent and Catholic school sectors, fulfilling a range of functions and dealing with a diversity of student issues. However, Australian academic research into the professional practice issues associated with the provision of school-based psychological services is rare. Therefore, this thesis sought to investigate a range of professional issues associated with the provision of school-based psychological services for Victorian school psychologists working in single and multiple schools in the government and non-government primary and secondary school sectors. In addition to surveying Victorian school psychologists, principals and teachers were also surveyed in order to ascertain their attitudes towards school-based psychological services. The sample consisted of 81 school psychologists, 21 principals and 86 teachers. The results revealed that school psychologists participate in a variety of activities, including a number of activities that reflect a systemic model of service delivery. They also deal with a broad range of student issues, some of which are quite serious in nature. However, the study also revealed a number of professional issues that were in need of improvement. Some of these included a lack of participation in regular supervision for school psychologists, school psychologists' dissatisfaction with some industrial and professional conditions associated with their role and differences in attitudes between psychologists, principals and teachers regarding the activities and responsibilities of school psychologists. Results from the study provide plausible evidence for the need to support school psychologists in the valuable work that they do within schools through improved industrial conditions, appropriate professional development, and regular supervision. Furthermore the results also reveal a need to educate and participate in dialogue with the educational community in order to increase understanding of school psychologists' roles and professional responsibilities.