Attitudes can affect how a person thinks and acts (Omolara & Adebukola, 2015; Salema, 2015). Therefore, it is important to be aware of teachers' attitudes and beliefs and how these important factors impact their thought processes and classroom instructional practices. If these beliefs appear to be having a negative impact on teachers' attitudes, it is necessary to help them learn how to teach more effectively (Clark & Peterson, 1986; Richardson, 1996). The main purpose of this study was to examine attitudes of Saudi Arabian K-12 education teachers toward inclusion and to determine whether the professional development programs currently offered in Saudi Arabia change or impact teacher attitudes toward inclusion. The researcher conducted a qualitative study utilizing semi-structured interviews with K-12 education teachers in Saudi Arabia to examine their attitudes and perspectives on inclusion and related assessment/instruction as well as how participation in professional development opportunities may impact or change their attitudes toward inclusion. Six themes emerged from the interviews: (a) different interpretations of inclusion, (b) professional development program, (c) perception of the need for accommodations and modifications, (d) assessment and instruction, (e) parents' impact on teachers' attitudes, and (g) recommendation to improve inclusive practices. Subsequently, 13 sub-themes emerged from the interviews, including: (a) the type of professional development program, (b) the outcomes of the professional development program, (c) the need for instruction and assessment, and (d) the need for professional development on instruction and assessment. Implications for improving inclusion, professional development programs, as well as instruction and assessment are included. Based on the results, several recommendations for practice and future research are suggested.