  We calculate the Collins fragmentation function in the framework of a
spectator model with pseudoscalar pion-quark coupling and a Gaussian form
factor at the vertex. We determine the model parameters by fitting the
unpolarized fragmentation function for pions and kaons. We show that the
Collins function for the pions in this model is in reasonable agreement with
recent parametrizations obtained by fits of the available data. In addition, we
compute for the first time the Collins function for the kaons.
