There has been no shortage of reviews of the implementation literature. Generally, it is suggested that the modern literature has moved through three phases (for example, Goggin et al, 1990; Hill and Hupe, 2002; Howlett and Ramesh, 2003; Schofield and Sausman, 2004). The first phase was triggered by the contributions of Pressman and Wildavsky (1973), Bardach (1977), and others. A flurry of writing emerged on the gap between policy intentions and the reality of program delivery in the US and other jurisdictions, considerable introspection about the limitations of social science research and ambitious ideas and solutions informing policy-making and the design of programs, and strong interest in discerning what interventions worked. Recognition of and debate over the implementation challenge was a defining moment for the modern policy literature, producing important strands of inquiry on implementation, evaluation, and knowledge utilisation that further defined the field and became insinuated into the ‘policy cycle’ heuristic (see Howlett and Ramesh, 2003; Pal, 2001; Bridgman and Davis, 2000; Hogwood and Gunn, 1984) but distinguished it from the early policy sciences approach (Lerner and Lasswell, 1951).

A second stream of writing focused on searching for useful theoretical perspectives and frameworks on implementation. This included work seeking to determine the most productive vantage points for thinking about how to anticipate and work through implementation challenges, which included the interesting debate over ‘top-down’ (forward-mapping) and ‘bottom-up’ (backward-mapping) approaches (Elmore, 1979; Berman, 1978), increasingly sophisticated efforts to develop frameworks and more sophisticated analytic tools that addressed the complexity of implementation (Mazmanian and Sabatier, 1983), and the sustained efforts to find better efforts to monitor and measure the impact of policy interventions (e.g. Williams et al, 1982). Arguably, this latter stream of research has built the most momentum over the years, particularly in the US, leading to a huge consulting industry dedicated to evaluation and quasi-experiments of program implementation, and effectively has defined the work supported by the Association for Public Policy Analysis and Management for the last two decades.

Like all fields, many of its early strands of writing endure as important lines of thinking in their own right. Howlett and Ramesh (2003) have suggested that more recent inquiry in implementation has tapped into game theory, public choice and principal-agent models to frame implementation challenges and guide empirical research. Considerable attention has focused on how instruments can be wielded and used in combination to achieve policy goals as well as different sectoral and national styles for approaching design and implementation (Linder and Peters, 1990; Howlett, 1991; Howlett, 1993). Recently, there has been renewed interest in implementation in the context of whole-of-government and multi-level governance perspective (Schofield and Sausman, 2004) and the challenge of managing complexity and networks more generally (O’Toole, 2004).

However, like the knowledge utilisation literature (though not as thoroughly), one senses that the literature on implementation has dissipated as a coherent field into specific lines of inquiry, effectively a victim of its success. Despite its status as a foundational stone in the policy tool-kit, many of the themes associated with implementation are taken up under different rubrics, such as horizontal management, whole-of-government, evaluation research, governing instruments, network analysis, etc. (Hill and Hupe 2002). Relatively few scholars march forward waving the implementation flag. And, despite the interesting theorising still occurring, and recent resurgence in interest in implementation (Schofield and Sausman, 2004), there is little evidence of applying implementation theory to practice and engaging practitioners in the emerging challenges of implementation, a style that was the hallmark when the literature first burst out (O’Toole, 2004).

This sketch of the implementation literature should suggest that contributors have done a good job of recognising complexity over the years, and thinking carefully about the analytic challenges of anticipating implementation issues; the mix, qualities and merits of different policy instruments for an implementation perspective; and the evolutionary and emergent quality of handling implementing policies and programs, a process of negotiation, adjustment and learning as managerial strategies. All of these themes and lessons should resonate even more in today’s arguably more complex policy-making landscape. However, Bardach’s early musings about building the right organisational and institutional capacities to mitigate implementation challenges has not received much attention over the years, and at best is only implicitly addressed in the field. This, combined with the lack of dialogue with practitioners on implementation challenges in recent years and the fact that several governments have recently considered or created units in their core executive to inform the upstream of policy development and to provide central oversight of implementation, suggests that the study of implementation units at the apex of governments is a timely and potentially fruitful line of inquiry.