Background  Offering informed choice in screening is increasingly advocated, but little is known about how evidence‐based information about the benefits and harms of screening influences understanding and participation in screening.Objective  We aimed to explore how a bowel cancer screening decision aid influenced decision making and screening behaviour among adults with lower education and literacy.Methods  Twenty‐one men and women aged 55–64 years with lower education levels were interviewed about using a decision aid to make their screening decision. Participants were purposively selected to include those who had and had not made an informed choice.Results  Understanding the purpose of the decision aid was an important factor in whether participants made an informed choice about screening. Participants varied in how they understood and integrated quantitative risk information about the benefits and harms of screening into their decision making; some read it carefully and used it to justify their screening decision, whereas others dismissed it because they were sceptical of it or lacked confidence in their own numeracy ability. Participants’ prior knowledge and beliefs about screening influenced how they made sense of the information.Discussion and conclusions  Participants valued information that offered them a choice in a non‐directive way, but were concerned that it would deter people from screening. Healthcare providers need to be aware that people respond to screening information in diverse ways involving a range of literacy skills and cognitive processes.