A historical look at theories of change in early childhood education research

• After decades of program implementation and evaluation, the early childhood education (ECE) field needs to move towards more effective and efficient strategies. One tool that has been developed to support this shift is theory of change (TOC). Though TOCs have been widely recognized for their potential utility, the extent to which they have been employed consistently in ECE research is unclear. In this paper, we draw upon a comprehensive, systematically developed archival database of high-quality ECE evaluations (N = 277) conducted over nearly five decades (1960–2007) to explore how the field has historically described and measured TOCs. We find that some components of TOCs have been used widely, and also that evaluators have increasingly measured implementation fidelity and standardization of program strategies over time. However, we additionally find that most ECE research has yet to move beyond the investigation of overall impacts towards more precise explanations of causal pathways. Instead, it remains common to focus on understanding whether a program is “effective” but relatively rare to explore how, why, for whom, and under what conditions an ECE program does or does not work.