Objective: Our objective was to understand the factors that determine whether an adult who is eligible for cochlear implantation (CI) choose to take up or not take up the implant. Design: We conducted a qualitative in-depth interview study, informed by grounded theory methods of constant comparison to build a theory to describe why and how people decide to opt for CI or not. Study sample: Our samples were patients from an audiology service in England. Results: Our results describe the key factors in weighing up risks and benefits. These are influenced by living context and support, information and social identity. We identify the key features that impact decision making for adults eligible for cochlear implants. The importance of the patient lifeworld view is discussed. Conclusions: This qualitative study provides the first in depth examination of how and why patients do and do not take up the offer of cochlear implants. It highlights the complex and iterative nature of this decision making and the individualised risks that trade off benefits of implantation.