In this chapter we learned about extending the CRM using plug-ins, custom workflows, and actions. We discussed all the options available in plug-ins and workflows. In this chapter we enhanced our library management system by adding new plug-in validation. We developed a custom workflow to add members to the book promotion marketing list. We learned how can we design actions and call them using workflows. We also discussed how we can register plug-ins on custom messages created using actions. In the next chapter, we are going to build an application tracking system.