The Evolutionary Map of the Universe (EMU) is a proposed radio continuum surveyof the Southern Hemisphere up to declination + 30°, with the AustralianSquare Kilometre Array Pathfinder (ASKAP). EMU will use an automated sourceidentification and measurement approach that is demonstrably optimal, tomaximise the reliability and robustness of the resulting radio sourcecatalogues. As a step toward this goal we conducted a “DataChallenge” to test a variety of source finders on simulated images. Theaim is to quantify the accuracy and limitations of existing automated sourcefinding and measurement approaches. The Challenge initiators also tested thecurrent ASKAPsoft source-finding tool to establish how it could benefit fromincorporating successful features of the other tools. As expected, most findersshow completeness around 100% at ≈ 10σ dropping to about 10% by≈ 5σ. Reliability is typically close to 100% at ≈10σ, with performance to lower sensitivities varying between finders. Allfinders show the expected trade-off, where a high completeness at lowsignal-to-noise gives a corresponding reduction in reliability, and vice versa.We conclude with a series of recommendations for improving the performance ofthe ASKAPsoft source-finding tool.