We have developed an order of magnitude model for the the complete motion - translation and rotation - of spheroidal microparticles under the influence of intense optical landscapes and laminar flow using force and torque balances within the system. Our fields of interest are periodic interference profiles, sometimes termed optical landscapes, that can be formed by simple holography. When given an arbitrary landscape, our model predicts that, in general, spheroidal particles become trapped at a lower potential threshold than do spherical particles of an equivalent volume. In addition, we show that optical landscapes exhibit exponential trapping selectivity based on particle size and shape, effectively adding a further dimension of control over which to trap, influence, and sort particles within the same flow.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.