Early childhood professionals have an important role in supporting young children's interest and engagement in STEM education. This study explores conceptualisations of STEM and beliefs about its importance in early childhood held by early childhood professionals. The "Early Childhood STEM Habits of Mind Framework," described in this paper, was used as the key analytical lens for the analyses of data from 117 early childhood professionals who completed a written survey before engagement in a STEM professional learning workshop. Results show that conceptualisations of STEM education held by the early childhood professionals related to its constituent disciplines; play-based and/or hands-on learning experiences; and the development of habits of mind. STEM was perceived to be important in early childhood, albeit ranking behind children's social-emotional development. This study highlights the potential utility of the Early Childhood STEM Habits of Mind Framework in supporting: (a) planning for integrated STEM learning experiences and (b) more holistic understandings and a shared language, among early childhood educators, parents and children, concerning STEM education.