In 1996 the Health Education Board for Scotland (now NHS Health Scotland) began a process of developing a 'settings'-based framework that would inform health promotion work across Scottish health services--the Health Promoting Health Service Framework (HPHS). It took the form of a flexible guidance document, attending to the foundations of integrated and sustainable health promotion practice via specific areas like partnership work, policy development and staff health. The project has subsequently been progressed over an extended period, comprising three phases: an initial development of the resource; piloting of the framework; and a wider assessment of implementation and initial impact. This paper reports on the latter phase. Within the context of various issues pertaining to the evaluation of a 'settings' approach and based on the use of case study methodology in nine HPHS pilot sites, this paper reports on the latter 2 year phase. This involved ongoing concern for understanding intervention processes and a growing interest in intervention outcomes and the paper reports on findings in each of these domains. In relation to outcomes, some positive gains in various indicators were detected though significant problems were experienced in this aspect. More significantly, the work was able to gain insights into what we call 'necessary conditions' of implementation. We theorize a range of 'contextual' factors (e.g. responsiveness to health improvement policy agendas) and project specific 'mechanisms' (e.g. providing skilled support) and present these as a nexus of conditions required for effective implementation of health promotion practice within explanatory models. Most significantly, we stress the relative frailty of any settings implementation strategy based simply on the uncoordinated dissemination of a tool or resource.