Abstract: Magnetic nanoparticles are promising candidates for use in biomedical applications as remote sensors of biophysical properties, thermal therapy agents, and detectors of specific biomolecules. Many approaches have been used to model magnetic nanoparticle behaviors in these applications to varying degrees of success. In this thesis, I study the most general non-equilibrium methods used to describe rotational dynamics. The characteristic rotational timescales of the particles are developed and critically evaluated conceptually and mathematically. Several approximate models are tested for their range of validity. A new apparatus is theoretically designed and then implemented, enhancing sensitivity to particle magnetizations in an oscillating field and increasing the accuracy of measurements of the environment surrounding the particles. Several other applications beyond sensing are successfully simulated computationally in order to give insight into the two mechanisms of rotation and suggest possible optimizations through an increased understanding of the nanoparticle physics.