This study reports the findings of three randomized survey design experiments implemented in different seasons of the agricultural calendar among Fairtrade coffee households in rural Ethiopia. The design focuses on the random allocation of the same survey instrument across child and proxy respondents for the measurement of child labor statistics. Our findings show the work of girls in agricultural settings is systematically underreported by the head of household relative to the child’s reports. Underreporting is explained by the child/proxy gender mismatch as differences in child labor reports ranges from 7 to 10 percentage points for girls when the proxy respondent is male. On the contrary, no reporting differences are found for boys across all seasons when the head of household is male. The magnitude of the child labor underreporting is larger among households with mixed child gender composition relative to households with homogeneous child gender composition. Underreporting by the proxy respondent, relative to the child’s own report, is not observed across other related outcomes such as schooling and household chores. Knowledge of Fairtrade standards and the degree and scope of effective commercial links between farmers and Fairtrade cooperatives do not have a systematic differential effect on the proxy reporting of child labor.