Over the past 10 years, early childhood professionals have been increasingly influenced by cultural-historical theory. In order to support professionals evolving their practice, the Australian government commissioned a set of cultural-historical resources specifically designed to build literacy and numeracy experiences for children from birth to the age of five years. This paper reports on an investigation of how teachers and families used the tools for supporting concept formation in literacy and numeracy and how they came to understand cultural-historical theory. A sample of 349 people (families, and qualified and unqualified early childhood professionals) were either surveyed online or interviewed in relation to the resources. The findings indicate that teachers focused more explicitly on cognitive outcomes for children as a result of using the resources, and most families interacted differently with their children in everyday situations after having piloted the resources. (Contains 2 figures and 3 tables.)