Abstract
Background

Uptake of colorectal cancer screening programmes needs to be improved or at least maintained in order to achieve projected reductions in mortality and morbidity. Understanding the origins of non‐participation in screening is therefore important.
Objective

To explore the beliefs and experiences of individuals who had not responded either to their screening invitation or reminder.
Design

A qualitative study using in‐depth interviews with non‐participants from England's population‐based colorectal cancer screening programme. Data collection and analysis were carried out using a grounded theory approach, with an emphasis on the constant comparison method, and continued until saturation (27 interviews).
Findings

The interviews provided an in‐depth understanding of a range of reasons and circumstances surrounding non‐participation in screening, including contextual and environmental influences as well as factors specific to the screening test. Non‐participation in screening was not necessarily associated with negative attitudes towards screening or a decision to not return a kit. Reasons for non‐participation in screening included not feeling that participation is personally necessary, avoiding or delaying decision making, and having some degree of intention to take part but failing to do so because of practicalities, conflicting priorities or external circumstances. Beliefs, awareness and intention change over time.
Discussion and conclusions

A range of approaches may be required to improve screening uptake. Some non‐participants may already have a degree of intention to take part in screening in the future, and this group may be more responsive to interventions based on professional endorsement, repeat invitations, reminders and aids to making the test more practical.