Learn about a new scalable particle tracking framework in MFEM through this 21-minute conference talk from the 2025 MFEM Workshop. Discover how to accurately and efficiently model billions of particles computationally at-scale for research in electromagnetics and fluid dynamics. Explore key features including support for arbitrary "fields" (vector data of any dimension), "tags" (integer data), and global particle identifiers, along with MPI rank rebalancing capabilities and seamless integration with existing MFEM data structures like Vector for GPU acceleration. Examine IO functionality for visualizing particle trajectories in GLVis and ParaView, and see practical demonstrations through new and improved miniapps including electromagnetics examples and an incompressible Navier-Stokes particle solver. Gain insights into how this framework addresses the computational challenges of large-scale particle simulations while leveraging MFEM's high-order mathematical calculation capabilities for scientific computing applications.