The most prominent electrical signal which can be recorded from the hippocampus is called theta rhythm. Over the past 30 years there have been numerous attempts to relate this waveform to behavior. Theta has been associated with arousal, learning memory, attention, and most recently motor movement. While the relationship between one type of theta and certain kinds of movement is well established, a second type of theta shows no such relationship. In the present paper it is argued that the most parsimonious hypothesis relating theta to behavior is not the motor programming theory but a sensory-inhibition model. In this model theta is regarded as representative of general inhibition of systems not being used during motor behavior or alert immobility.