The open government data (OGD) movement has rapidly expanded worldwide with high expectations for substantial benefits to society. However, recent research has identified considerable social and technical barriers that stand in the way of achieving these benefits. This paper uses sociotechnical systems theory and a review of open data research and practice guidelines to develop a preliminary ecosystem model for planning and designing OGD programs. Findings from two empirical case studies in New York and St. Petersburg, Russia produced an improved general model that addresses three questions: How can a given government's open data program stimulate and support an ecosystem of data producers, innovators, and users? In what ways and for whom do these the ecosystems produce benefits? Can an ecosystem approach help governments design effective open government data programs in diverse cultures and settings? The general model addresses policy and strategy, data publication and use, feedback and communication, benefit generation, and advocacy and interaction among stakeholders. We conclude that an ecosystem approach to planning and design can be widely used to assess existing conditions and to consider policies, strategies, and relationships that address realistic barriers and stimulate desired benefits. •Reviews open government data (OGD) benefits and barriers•Identifies key social and technical considerations for OGD program design•Develops an ecosystem model of stakeholders, policies, practices, relationships, and influences•Applies the model to case studies of New York and St. Petersburg•Suggests further testing and additional research