Landline random-digit-dialing (RDD) survey coverage problems due to cell phone-only households have led to a growing number of cellular telephone surveys being conducted at the national and state level to supplement traditional RDD surveys. We discuss the trade-off s of screening for cell phoneonly household/adults versus using a dual frame sample design that also includes households/adults with landline and cellular telephone service. We then discuss how the National Health Interview Survey and other surveys such as the CPS and ACS can be used to develop estimates of the size of the cell phone-only household/adult population for states and other subnational geographic areas.