The penetration rate of cellular phones has toped 80% in some countries. Even though it is still considerably smaller in the and many European countries, mobile phone numbers are included frequently in the sampling frames for telephone surveys. In 1999 and 2002, two small-scale pilot studies were conducted in to assess mobile communication devices for survey purposes. In both studies, a random sample of cell phone numbers was compared to a random home phone sample. Indicators for coverage error, nonresponse error, and measurement error were used to evaluate and compare the two samples. This paper summarizes results on field work, unit nonresponse, and measurement error in mobile phone surveys. Based on the two studies, data quality indicators for the mobile phone samples are compared to the home phone samples. Results indicate only a few data quality indicators differ greatly.