School policy interventions are at the core of research into school improvement, school change, and school effectiveness. In all of these research fields, however, different classifications are being used to identify school policy interventions. Most of the existing classifications are, moreover, based on too narrow a view on school policy practice: ignoring non-innovative interventions, focusing solely on educational interventions, or merely founded on interventions that have already been implemented. Finally, though these classifications aim to encompass school policy practice, hardly any of the present schemes is validated by representatives of this school practice. The lack of an interdisciplinarily applicable ordering instrument for school policy interventions, validated by educational practice, hinders the accumulation of knowledge in and between different research fields with regard to the use of school autonomy. Based on a mixed-method study amongst a cross section of Dutch secondary education school leaders, an interdisciplinarily and internationally applicable classification scheme for school policy interventions that is validated by educational practitioners is constructed in this study. To include the full spectrum of school policy practice, interventions are studied from a broad perspective. The definition is not confined to innovative interventions, it includes all school policy areas, and it encloses interventions that are seriously considered, but not necessarily initiated. The active involvement of educational practitioners is pursued in all stages of the study for an increased validation of the classification scheme by educational practitioners.

In most education systems, school leaders (including all equivalent terms) play a key part in school policy decision-making, with final responsibility and accountability for all school policy practice. Pont, Nusche and Moorman define school leadership as “the key intermediary between the classroom, the individual school and the education system as a whole” (2008, p. 16) in a rapidly changing society with continuously changing goals and objectives to be achieved by schools. With the gradual shift towards more decentralization, often accompanied by an increased accountability regime and curriculum control (Pont et al., 2008), decision-making responsibility and accountability of school leaders increased (Leithwood, 2001; OECD, 2013). These shifts of autonomy and accountability are all the more relevant in light of the importance of school leadership on student outcomes and school improvement and achievement (e.g. Hallinger & Heck, 1998; Leithwood, 2001; Leithwood & Sun, 2012; Robert J Marzano, 2003; Robert J. Marzano et al., 2005; OECD, 2015; Pont et al., 2008; Scheerens, 2012).

Compared to school leaders in most other education systems, school leaders in the Netherlands operate in a highly autonomous policy context (OECD, 2012, 2013, 2014a; Pont et al., 2008). Within a framework of learning objectives, examinations and funding mechanisms that are set by the national government, administration of Dutch schools is highly decentralised compared to that in other OECD countries. According to Bal and De Jong (2007, p. 36), “Dutch education institutions have always had considerable freedom for the arrangement of education, didactics, the way in which the institutions work and teaching methods. Being offered freedom means having to make choices and the school leader plays a prominent part in making these choices.” One assumes that a high level of policy autonomy leads to a thematically diverse palette of potential school policy interventions that are under consideration. The classification of a diverse inventory should produce a classification scheme that is to include most school policy interventions present in other education systems. Herewith making it practicable for broad international and interdisciplinary usage.

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