Ensuring data security and compliance during cloud migration is a multi-step process. Firstly, understanding the regulatory landscape of your industry is crucial. This includes knowing what data can be moved to the cloud and what can't. Secondly, choosing a cloud service provider that offers robust security measures, including data encryption, firewalls, intrusion detection systems, and regular security audits is essential. Thirdly, it's important to have a clear data governance strategy that outlines who has access to what data. Finally, regular audits and compliance checks should be conducted to ensure ongoing compliance.