Background Community health workers play an important role in delivering health-care services, especially to underserved populations in low- and middle-income countries. They have been shown to be successful in providing a range of preventive, promotive and curative services. This qualitative study investigated the factors motivating or demotivating community health workers in urban settings in Delhi, India. Methods In this sub-study of the ANCHUL (Ante Natal and Child Healthcare in Urban Slums) implementation research project, four focus-group discussions and nine in-depth interviews were conducted with community health workers and medical officers. Utilizing a reflexive and inductive qualitative methodology, the data set was coded, to allow categories of motivating and demotivating factors to emerge. Results Motivating factors identified were: support from family members for their work, improved self-identity, job satisfaction and a sense of social responsibility, prior experiences of ill health, the opportunity to acquire new skills and knowledge, social recognition and status conferred by the community, and flexible work and timings. Negative experiences in the community and at health centres, constraints in the local health system in response to the demand generated by the community health workers, and poor pay demotivated community health workers in this study, even causing some to quit their jobs. Conclusion Community-health-worker programmes that focus on ensuring the technical capacity of their staff may not give adequate attention to the factors that motivate or discourage these workers. As efforts get under way to ensure universal access to health care, it is important that these issues are recognized and addressed, to ensure that community health worker programmes are effective and sustainable.