National planning policy in Scotland has increasingly embraced the value of creating 'well-designed places', within a broader 'placemaking' policy agenda. With gathering momentum since the turn of the millennium, Scottish planning policy has recognised the wealth of evidence for the holistic 'value' urban design provides, while wider interest in design-based responses to major policy challenges - including climate change and health inequalities - has grown more recently. However, consistently delivering new development which reflects the design ambition of national policy has proven challenging at local level. Supported by an ESRC collaborative studentship, this thesis addresses this disconnect, through qualitative case study research with West Dunbartonshire Council (WDC). WDC is a small local authority in a constrained post-industrial area in the west of Scotland which, since 2017, has made a strategic investment in its urban design governance capacity. Data was collected using: 42 semi-structured interviews with 37 'key informants'; archival work with national planning policy from 1999 to the present, WDC's planning policy and guidance from 2010 onwards, and planning application documentation from between 2016 and 2022 pertaining to four purposively selected 'sub-case' development sites and five other informative examples; and observations of West Dunbartonshire's built environment conducted between 2020 and 2022. A thematic analysis of interview transcripts was conducted using QSR NVivo software, while archival data informed analysis of national and local urban design policy and a structured analysis of design outcomes at the four 'sub-case' sites, which was based on a framework of design priorities developed from WDC policy. This thesis uses a novel theoretical framework which combines two distinct bodies of work, on 'design governance' and 'street-level bureaucracy', to understand how the local delivery of urban design is shaped by the wider neoliberalisation of state governance. The findings reveal the significance of leadership in establishing a design-oriented culture change within WDC, and how this has empowered front-line planners to prioritise design outcomes at street level, supported by a series of micro-level adaptations and design governance policy tools. Yet, the discretion of street-level planners is simultaneously constrained by a series of immediate pressures including resource shortages, and competing policy priorities such as the necessity of attracting real estate investment. The latter is a fundamental feature of West Dunbartonshire's development context, and findings suggest that the local manifestations of dominant planning concerns for economic growth and commercial viability are shaping how planners perceive design to serve traditional 'public interest' values. This is further compounded by the systemic austerity-driven requirement for planners to work with and through external partners, particularly private consultants, who routinely mediate between public authority and private development clients. The membership of WDC's Place and Design Panel, a design review panel which provides valuable design capacity and soft power in support of WDC's endeavours to reshape the local development market, exemplifies an increasing informality to this feature of contemporary planning practice. The thesis therefore makes a distinct contribution to existing literature by applying 'street-level' theory to research on 'design governance'. This, in turn, enables the exploration of urban design as an area of public policy, which is itself previously under-researched using theory on implementation. In highlighting the actors with shared responsibilities for design governance at the blurred boundary of the local state, the thesis also raises critical questions about how design governance ultimately serves the 'public interest', in light of the dominance of viability concerns and private sector capacity within contemporary planning. The thesis concludes that the cultural changes WDC has introduced show great promise for more consistently creating well-designed places, but that street-level planners within local authorities will require stronger support from policy and resource at national level if early results from West Dunbartonshire are to be maintained, and repeated.