This paper will discuss the findings of a retrospective travel survey with respect to what triggers change in commuter travel behaviour. The survey was conducted in Cape Town during August 2006, as part of a project commissioned by the Department of Transport to develop a strategic framework to guide the implementation of Travel Demand Management (TDM) strategies in South African cities. Data were collected in four residential areas (Wynberg/Plumstead, Steenberg/Seawinds/Coniston Park, Gugulethu, Mandalay/Mont Claire) in which a large portion of households fall within the R3,000-R6,000 income band, observed in other data sources as strategic from a car ownership and mode switching perspective. The paper will identify the different elements of a commuting trip decision as origin, destination, mode and departure time and then discuss the findings of the survey with respect to what events or shocks triggered a deliberate (or ‘preference-based’) – as opposed to habitual (or ‘scripted-based’) – reconsideration of usual behaviour for each of these trip elements. Events or shocks triggering deliberate reconsideration that led to both change and no change will be analysed. The paper will conclude with a discussion on the implications of these findings for the strategic targeting of TDM measures at people more susceptible to changing particular aspects of behaviour than others, and how triggers might be deliberately introduced through TDM intervention.