This article considers the ethical dimensions of efforts to develop professional practice with others, informed by literature on the ethics of intervention in education. Data are presented from three studies with workplace teams in early childhood education in Australia and New Zealand that have employed double stimulation within Change Laboratory activities. These data are used to exemplify how the use of double stimulation exposes issues such as agency, power, decision-making, cultural representation, and relationality in the transformation of professional practice. The central claim of the article is that researchers employing double stimulation to develop professional practice need to develop a nuanced understanding of the ethical complexities of formative efforts, both for themselves and for their fellow participants. The article concludes with a series of questions for researchers to consider when intervening in professional practice, including: "Who will likely benefit if we implement the changes we are planning?" and "Who and what is being transformed?"