Micropipette manipulation measurements quantified the pre-steady state binding kinetics between cell pairs, mediated by Xenopus cleavage stage cadherin. The time-dependence of the intercellular binding probability exhibits a fast-forming, low probability binding state which transitions to a slower-forming, high probability state. The biphasic kinetics are independent of the cytoplasmic region, but the transition to the high-probability state requires the third extracellular domain EC3. Deleting either EC3 or EC3-5, or substituting Trp2 for Ala reduces the binding curves to a simple, monophasic rise in binding probability to a limiting plateau, as predicted for a single site binding mechanism. The two-stage cadherin binding process reported here directly parallel previous biophysical studies, and confirms that the cadherin ectodomain governs the initial intercellular adhesion dynamics.