One size does not fit all in Prevention. This was evident at the Society for Prevention Research conference in San Francisco last week and it is true for prevention science and practice. But when is adaptation from accepted modes of working acceptable, and how much variation should be tolerated?

The practical problems of prevention practice were illustrated last week in presentations about two programs, one from the US and another from Africa.

Miguelina German and colleagues at Arizona State University have been testing parenting programs. As a rule interventions tend to frown heavily on the use of physical punishment. 'But where is the evidence?’ asked community members consulted about the introduction of the programs. 'What is wrong with smacking your children? It didn't do me any harm?'

This response led German and her colleagues to not only reassemble the available evidence, but also to prepare new materials that not only explained why smacking was ineffective but also how it can lead to a deterioration in children's behavior. Parents responded well to the materials.

When are such adaptations appropriate? German argues that they are necessary when there are low levels of engagement with the program. There is no point being hard line to the point that fewer people can benefit from the intervention.

Consistent with other findings on program fidelity, German argues that adaptations must not compromise the core logic of the program. There is no reason to give up on a strategy to reduce physical punishment, but there is every reason to explain the reasoning and justification in terms that make sense to specific cultural groups.

Nancy Padian from the University of California in San Francisco stumbled upon similar problems in relation to HIV prevention in South Africa and Zimbabwe. Cultural beliefs, including the myth that HIV cannot be transmitted between heterosexuals, have to be tackled sensitively. Padian also talked about the need to design evaluations in conditions that can be sustained in the real world. There is huge temptation for program designers with good resources to provide free healthcare and secure high rates of participation. Quite apart from questions of ecological validity there is the ethical issue of communities having to adjust to reduced resources once the experiment is complete and free healthcare is withdrawn.

In different ways, the various presentations on program adaptation spoke to the need for community and practitioner engagement in prevention science. A need that the President of the Society, Zili Sloboda, spoke so passionately about in a conversation with Prevention Action to be reported in Friday's edition.