At a time of increasing calls from policy makers for the use of "hard evidence" in driving decision-making at national and local levels in educational contexts, this article contributes to debates about evidence-based practice in early literacy research. It proposes that a reliance on studies designed to generate 'hard' evidence limits understanding about innovations and interventions, arguing that such reliance is not just problematic because interventions and innovations are interpreted differently in diverse sites, or because programmes need to be locally relevant, but because they are "constituted differently through different evaluation studies." The article draws on Law's notion of "method assemblage" to consider how different studies produce different assemblages that have implications for how innovations are conceived. These ideas are exemplified using studies scrutinised through a systematic literature review of one kind of literacy intervention, early years book-gifting, which aims to promote book-sharing in the home. The discussion focuses specifically on how books as mediating objects are instantiated in various ways through different studies, with different implications for how book-sharing, book-gifting and, ultimately, reading are understood. When considered together, these studies construct book-gifting in multiple ways, problematising and complicating the causal relations assumed in methodologies driving for "hard" evidence. Drawing on the book-gifting example, this article explores what might be gained by embracing "multiplicities", the multiple ways in which things--such as objects, activities, principles and indeed literacy interventions--are constituted through method assemblage. It argues that literacy evaluations can best serve children and their families, and the organisations, agencies and groups working alongside them, by seeking fluid, open and "generous" accounts of innovations and interventions. Such accounts, it is argued, are more likely to acknowledge the complex relationships and practices associated with early literacy and to generate new understandings and productive possibilities for early literacy learning.