The aim of this research was to examine nurses' and health care assistants' perspectives of infection control practice on one hospital ward and use this as the basis for the development, implementation and evaluation of an education and support programme for improving practice on the ward. In Phase I of the study, nurses and health care assistants were interviewed using a semistructured interview schedule to explore their views and anxieties about infection control practice and identify their priorities for practice development. Qualitative and quantitative analysis of these data revealed that respondents' concerns related primarily to the use of Contact Precautions for patients with Clostridium difficile associated diarrhoea (CDAD) and Methicillin resistant Staphylococcus aureus (MRS A). Structured observations of practice were employed to confirm the prevalence of the issues raised in relation to this and provide an understanding of their context. The findings of Phase I informed the design of an intervention to improve practice. This involved the development of a practice guideline on Contact Precautions and the availability of practical instruction and support during its implementation. In Phase II of the study, participant observations of practice were conducted to gain an understanding of nurses' and health care assistants' behaviour and in particular, their responses to the supportive intervention. Their perceptions of its impact on their practice were ascertained in Phase III using semi-structured interviews. Qualitative analysis of these data revealed that participants experienced great difficulty understanding and implementing infection control recommendations. Factors that may help explain this include nurses' and health care assistants' knowledge and skills in infection control, their personal belief systems and self-preservation instincts. In addition, the recommendation to use Contact Precautions for patients with infectious conditions such as CDAD and MRS A may itself counteract attempts to promote the routine use of infection control precautions in clinical practice. It is suggested that in relation to infection control, there may be a need to radically re-think the ways in which health care workers are educated and supported in practice. Moreover, it is argued that until the ambivalent evidence base relating to the use of Contact Precautions is resolved, messages about infection control are likely to generate confusion amongst health care workers.