Model-Based Systems Engineering (MBSE) methodologies, languages and tools have been used for many years and across many industries to define, solve, and manage problems and solutions of high complexity. But MBSE was traditionally employed on big Waterfall projects where it was common place to do your “Big Modeling Up Front” and throw models “over the fence” to the next phase of development. In addition, while traditional Agile development frameworks and best practices (e.g., Scrum, XP) have also been employed for many years, they didn’t explicitly provide guidance on how to integrate MBSE and Agile development. Fortunately, the Scaled Agile Framework (SAFe®) provides high-level guidance on how to apply MBSE on large-scale development projects. In this presentation, we will share practical best practices for performing Lean-Agile MBSE that anyone can apply on their program. Also, we will discuss a number challenges we have experienced with Lean-Agile MBSE and some ideas on how these challenges might be addressed in the future.