Motivation – Engineering judgment forms an integral part of the contaminated land risk assessments required to develop land in the UK (ODPM, 2004). This study investigated how the complex, uncertain site information is used by expert engineers in these assessments. Research approach – Site reports with different cue combinations were assessed and the findings were compared quantitatively to the predictions of three theories of decision making: Recognition-primed decision making (RPD), fast and frugal heuristics and the Lens model. Findings / Design – Support was found for a process of combining several sources of information simultaneously, rather than a matching heuristic in which cues are tested serially. Experts appear to focus on a limited set of information rather than treating all cues equally as recommended in current guidance (Defra, 2004). Research limitations / Implications – The site reports and assessment format, although reflective of real projects, was simplified to meet time constraints of the participants. The sample size used was sufficient to fit the chosen models to the average expert response, though insufficient to enable predicting of individual responses. Both of these aspects could be addressed with further research. Originality / Value – An understanding of expert judgment in contaminated land assessment can be used to improve future training and guidance required to address the current industry skill shortage (ASC, 2008). Take away message – Despite the apparently holistic approach to contaminated land risk assessment described in the qualitative responses to this study, the numeric analysis of the expert’s rating of risk showed that it was based on a limited number of cues.