Time-domain analysis is used to derive criteria on the stability of sampled-data feedback systems comprising a time-varying plant, a time-varying non-linearity, and a sampler which may exhibit any given periodic or aperiodic sampling mode. Three aspects of the systems dynamic response are given a unified treatment: boundedness, unboundedness, and asymptotic decay. In addition to qualitative criteria, the results provide quantitative bounds on the system response, and indicate its explicit dependence on the sampling mode.