Novel technologies such as augmented reality and computer perception lay the foundation for smart assistants that can guide us through real-world tasks, such as cooking or home repair. However, the nature of real-world interaction requires assistants that adapt to users’ mistakes, environments, and communication preferences. We propose Adaptive Multimodal Assistants (AMMA), a software architecture for task guidance with generated adaptive interfaces from step-by-step instructions. This is achieved through 1) an automatically generated user action state tracker and 2) a guidance planner that leverages a continuously trained user model. The assistant also adjusts its guidance and communication delivery methods based on observed user performance as well as implicit and explicit user feedback. We demonstrated the viability of AMMA by building an adaptive cooking assistant running in a high-fidelity virtual reality-based simulator. A user study of the cooking assistant showed that AMMA can reduce the task completion time and the number of manual communication methods changes.