Given the prominence of dryland salinity as a resource management problem in Australia, it might be expected that farmers would keenly monitor the levels of saline groundwater under their farms. However, many farmers choose not to monitor, in some cases even when they have previously installed bores suitable for this purpose. We investigated this apparent paradox by analysing the monitoring behaviour of a group of farmers in the Jerramungup region of southern Western Australia. The farmers are unusual in displaying a very high rate of monitoring compared with other regions, although this rate has fallen over the past decade. A range of physical, economic and social influences on monitoring behaviour are identified by statistical analysis of survey and physical data. A key finding is that farmers who are using the information from monitoring to assess salinity management strategies implemented on their farms are likely to monitor more frequently. This suggests that monitoring frequency may be driven in large part by the availability of suitable salinity management practices that can be implemented, in contrast to the view that adoption of salinity management practices may be enhanced by programs that encourage monitoring.