ObjectivesThis study applies three latent interaction models in the theory of planned behaviour (TPB; Ajzen, 1988, Attitudes, personality, and behavior. Homewood, IL: Dorsey Press; Ajzen, 1991,Organ. Behav. Hum. Decis. Process.,50, 179) to quitting smoking: (1) attitude × perceived behavioural control on intention; (2) subjective norms (SN) × attitude on intention; and (3) perceived behavioural control × intention on quitting behaviour.MethodsThe data derive from a longitudinal Internet survey of 939 smokers aged 15–74 over a period of 4 months. Latent interaction effects were estimated using the double‐mean‐centred unconstrained approach (Linet al., 2010,Struct. Equ. Modeling,17, 374) inLISREL.ResultsAttitude × SN and attitude × perceived behavioural control both showed a significant interaction effect on intention. No significant interaction effect was found for perceived behavioural control × intention on quitting.ConclusionsThe latent interaction approach is a useful method for investigating specific conditions betweenTPBcomponents in the context of quitting behaviour. Theoretical and practical implications of the results are discussed.Statement of contributionWhat is already known about the subject?Although research on quitting smoking in the context ofTPBis gradually growing, the exploration of latent interaction effects ofTPBvariables on quitting intentions and subsequent quitting behaviour is scarce. The double‐mean‐centred unconstrained approach is proposed as a new and user‐friendly alternative to estimate interaction effects. This study investigated threelatentinteraction effects inTPB, as applied to quitting smoking using a double‐mean‐centred unconstrained approach.What does this study add?This study provides evidence for an interaction effect for attitude × subjective norm on intention and attitude × perceived behavioural control on intention.No significant interaction effect was found for perceived behavioural control × intention on quitting behaviour.This study latent variable approach used to investigate interacti