Although low frequency challenging behaviour (that which occurs less than once a day) is common, very little research has been done into its analysis or treatment. It is suggested that the methods of analysing high frequency challenging behaviour, such as experimental functional analysis, will not be applicable with low frequency challenging behaviour. The use of correctional analysis of case records is considered as a method for generating hypotheses as to why a client is showing low frequency challenging behaviour. It is noted that using simple correlations is a method that can provide only limited information as to the relationship between a challenging behaviour and other events. A method that can reveal more about the temporal relationship between environmental events and challenging behaviour is time base lag sequential analysis. Three case studies are presented in which time base lag sequential analysis was used to analyse the relationship between challenging behaviour and possible causal factors.