Objective To understand why skilled birth attendance—an acknowledged strategy for reducing maternal deaths—has been effective in some settings but is failing in Pakistan and to demonstrate the value of a theory‐driven approach to evaluating implementation of maternal healthcare interventions. Design Implementation research was conducted using an institutional ethnographic approach. Setting and population National programme and local community levels in Pakistan. Methods Observations, focus group discussions, and in‐depth interviews were conducted with 38 Community Midwives (CMWs), 20 policymakers, 45 healthcare providers and 136 community members. A critical policy document review was conducted. National and local level data were brought together. Main outcomes Alignment of programme theory with real‐world practice. Results Data revealed gaps between programme theory, assumptions and reality on the ground. The design of the programme failed to take into account: (1) the incongruity between the role of a midwife and dominant class and gendered norms that devalue such a role; (2) market and consumer behaviour that prevented CMWs from establishing private practices; (3) the complexity of public–private sector cooperation. Uniform deployment policies failed to consider existing provider density and geography. Conclusions Greater attention to programme theory and the ‘real‐world’ setting during design of maternal health strategies is needed to achieve consistent results in different contexts.