Objective To highlight key methodological issues in studying insurance dynamics and to compare estimates across two commonly used surveys. Data Sources/Study Setting Nonelderly uninsured adults and children sampled between 2001 and 2011 in the Medical Expenditure Panel Survey and the Survey of Income and Program Participation. Study Design We utilized nonparametric Kaplan–Meier methods to estimate quantiles (25th, 50th, and 75th percentiles) in the distribution of uninsured spells. We compared estimates obtained across surveys and across different methodological approaches to address issues like attrition, seam bias, censoring and truncation, and survey weighting method. Data Collection/Extraction Methods All data were drawn from publicly available household surveys. Principal Findings Estimated uninsured spell durations in the MEPS were longer than those observed in the SIPP. There were few changes in spell durations between 2001 and 2011, with median durations of 14 months among adults and 5–7 months among children in the MEPS, and 8 months (adults) and 4 months (children) in the SIPP. Conclusions The use of panel survey data to study insurance dynamics presents a unique set of methodological challenges. Researchers should consider key analytic and survey design trade‐offs when choosing which survey can best suit their research goals.