Many of the variables are difficult to measure - for example,  perceived seriousness, perceived susceptibility or level of self-efficacy.

The model assumes people are rational in their decision-making - but Kahneman has shown us that we rely on System 1 thinking.

Research on optimism bias (e.g. Weinstein, 1987) shows that people rate their personal risk of developing health problems as less than for other people. Turner (1988) found that student rate other students’ risk of contracting HIV as higher than their own.

Assumes that behavioural change is a conscious choice.  This may not always be true, as in the case of addiction.

Ignores the role of social and environmental factors.

Unlike the Health Belief Model, the SCT includes environmental factors and seeks to change social norms.

Programs such as the Sabido Method have been effective in changing behaviour.

The theory does not explain why people choose to change.

It is difficult to measure levels of "self-efficacy," as it is based on self-reported data.

In many studies on the effectiveness of SCT, self-efficacy has not shown to be a valid predictor of behavioural change.