A method and system for workforce planning in one aspect provide an optimization model that produce, based on the availability profile and the demand profile of skill types, a workforce plan recommending a combination of actions. The combination of actions may include hiring, contracting and cross-training. The optimization model considers constraints such as minimum residence time that a resource unit needs to spend in a skill-type that it gets cross-trained into or hired into, minimum acceptable contracting duration for a contracted skill type, first order and higher orders of cross-training for a skill type, with lead-time for training, one or more system rules associated with transfer sequences, or targets on service levels and resource utilization, or combinations thereof, in determining the workforce plan.