Preliminary results from the July-December 2006 National Health Interview Survey (NHIS) indicate that the number of households with only wireless telephones continues to increase. During the last 6 months of 2006, more than 3 out of every 20 American homes (15.8%) did not have a landline telephone. Of those homes without a landline telephone, most had at least one working wireless telephone. Preliminary results from NHIS suggest that more than one out of every eight American homes (at least 12.8%) had only wireless telephones during the second half of 2006. These are the most up-to-date estimates available from the federal government concerning the size of this population.