The operation control principle is still unclear regarding how to coordinate virtual inertia and damping considering both frequency stability and transient synchronization stability. In this chapter, an Adaptive Inertia and Damping Coordination (AIDC) control strategy is proposed for grid-forming converters to improve transient stability. The proposed AIDC strategy adaptively adjusts the virtual inertia and damping coefficients based on real-time conditions of operation frequency deviation and its rate of change of frequency (RoCoF). The virtual inertia is designed to dynamically increase in the accelerated area and decrease in the decelerated are, and the virtual damping coefficient is designed to increase and enlarge the positive virtual damping effect during the whole accelerated/decelerated transient process. In addition, the proposed AIDC strategy is realized through the practical arctan-function control method with limited boundaries, which can assist engineers. The effectiveness of the proposed AIDC strategy is validated through hardware-in-the-loop experiments.