Language comprehension delays in pre-schoolers are predictive of difficulties in a range of developmental domains. In England, early years practitioners are required to assess the language comprehension of 2-year-olds in their care. Many use a format based on the Early Years Foundation Stage Unique Child Communication Sheet (EYFS:UCCS) in which the child's language comprehension is assigned to an age band based on written guidance. Seventy 2.5-3-year-olds were assessed on the comprehension component of the Preschool Language Scale (PLS) by psychology graduates. Early years practitioners assessed language comprehension in the same children using the EYFS:UCCS and the WellComm, which involves some direct testing. The EYFS:UCCS had poor sensitivity and specificity, and the understanding section did not correlate with the PLS. The WellComm had good to acceptable levels of sensitivity and specificity and significantly correlated with the PLS. Early years setting staff can accurately assess the language comprehension of 2-year-olds if provided with a tool which gives specific instructions on administration, but current frequently used procedures (EYFS:UCCS) are not fit for this purpose.