The entrance construction behaviors of Aliatypus thompsoni and Antrodiaetus unicolor (family Antrodiaetidae) and one member of the genus Hebestatis (family Ctenizidae) are described from direct laboratory observations of incomplete and complete construction sequences. These descriptions were compared to test the hypotheses that the collar door of Antrodiaetus is the primitive construct in the family Antrodiaetidae and that the evolutionary shift from one entrance form to the other requires little genetic or neurophysiological change.