Software development process tailoring is an emerging practice in today's IT industry. A limited number of research works have been published in this area. The existing process tailoring approaches describe similar set of operations and do not provide proper guidelines on performing process tailoring. These tailoring approaches mainly focus on large companies and tailor only one or two agile methods instead of providing specific guidelines on tailoring agile based methodologies. Unlike large companies, attention has not been given to small and medium sized companies. The present study addresses this limitation, identifies process tailoring operations, key processes of agile based methodologies and uses them for tailoring processes for small and medium sized companies. Qualitative research methods are used to identify and validate tailoring operations and key processes of agile based methodologies. The results show that performing these tailoring operations to tailor key agile based processes is an effective and applicable process tailoring approach for small and medium sized companies. The outcome of the present study would provide basis for formulating process tailoring framework for small and medium sized companies. © 2014 IEEE.