No. While prior mindfulness practice may motivate individuals to take MBSR, the MBSR program and instructor have no expectation that participants have experience with meditation or yoga or any other mindfulness practice. Everyone will have the opportunity to explore and experience mindfulness while having a skilled teacher to guide and help answer questions about practice.
For those that have experience with meditation or yoga in the past, the course can be a good refresher to rebuild a strong daily practice.
Do I need to have experience with meditation or yoga prior to the course?