Measurement error can be very difficult to assess and reduce. While great strides have been made in the field of survey methods research in recent years, many ongoing federal surveys were initiated decades ago, before testing methods were fully developed. However, the longer a survey is in use, the more established the time series becomes, and any change to a questionnaire risks a break in that time series. This article documents how a major federal survey – the health insurance module of the Current Population Survey (CPS) – was redesigned over the course of 15 years through a systematic series of small, iterative tests, both qualitative and quantitative. This overview summarizes those tests and results, and illustrates how particular questionnaire design features were identified as problematic, and how improvements were developed and evaluated. While the particular topic is health insurance, the general approach (a coordinated series of small tests), along with the specific tests and methods employed, are not uniquely applicable to health insurance. Furthermore, the particular questionnaire design features of the CPS health module that were found to be most problematic are used in many other major surveys on a range of topic areas.