There is considerable literature describing the use of Change Laboratory as a simultaneous research and intervention methodology in workplace settings. However, there is limited literature describing Change Laboratory from the researcher-facilitator perspective. This paper examines the ethical dimensions of Change Laboratory from this perspective and specifically how a 'rule of care' became a conscious rule. The context is a series of Change Laboratories implemented with Centre Directors and Educational Leaders from early childhood education and care centres in Darwin and Melbourne, Australia. Based on our analysis we attribute the emergence of this rule to a particular vulnerability of the participants: that they were all recruited from centres that had been publicly designated as "Working Towards National Quality Standard" requirements for quality early childhood education and care practices. We present evidence of this 'rule of care' in our work as researcher-facilitators from our data. We conclude that attention to a 'rule of care' is necessary to support transformation, particularly for vulnerable participants such as Educational Leaders.