Molecular and cellular mechanisms by which microtubules and associated motor proteins participate in vesicle transport and ciliary function. Microtubules are cytoskeletal filaments that provide structural support for cells and also play important roles in cells as they serve as tracks for vesicle transport, form the mitotic spindle for separation of chromosomes during cell division, and comprise the axoneme in cilia and flagella. Defects in these microtubule-based functions are associated with a variety of diseases, including neurodegeneration, cancer, and ciliopathies. Our work is focused on the molecular and cellular mechanisms by which microtubules and associated motor proteins participate in vesicle transport and ciliary function. Motor proteins use the energy of ATP hydrolysis to carry cargoes along microtubule tracks. This is an essential function in all cells but is particular important in polarized cells such as neurons which have a high transport load due to the long distances and choice of direction (axon versus dendrite) that cargoes must be carried. Our work in axonal transport is focused on how kinesin motor proteins bind to their cargoes and become activated for transport. We are also interested in how directional choices are made by kinesin motors and are exploring the hypothesis that there is a “tubulin code” in which post-translational modifications of subsets of microtubules provide directional cues to kinesin motors. Our work in cilia is focused on the role of kinesin motors in the assembly, function and disassembly of primary cilia during the G1 phase of the cell cycle.