In this paper, impact dynamics of a five-link biped walking on level ground are studied, and the results are used to correlate the gait parameters with the contact event following impact. The conventional five-link biped kinematic model is improved such that, for the first time, the explicit solution for the external impulses is obtained in a detailed but compact form. Such a solution reveals that the direction of the swing tip velocity prior to impact is a key factor dictating the upcoming contact event and the slippage. The conventional conditions to warrant the types of impact are expanded to make them sufficient. The aforementioned results are used in the parametric analysis to predict the contact event after impact. Such a prediction is important for proper dynamic modeling, motion planning, and control of the upcoming supporting phase.