Childcare providers are often "first responders" for suspected child abuse, and how they understand the concept of "reasonable suspicion" will influence their decisions regarding which warning signs warrant reporting. Objective The purpose of this study was to investigate how childcare providers interpret the threshold for reporting suspected abuse, and to consider the implications of these findings for professional training and development. Method A convenience sample of 355 childcare providers completed the Reasonable Suspicion of Child Abuse survey to quantify what likelihood of child abuse constitutes "reasonable suspicion." Responses were examined for internal consistency, evidence of a group standard, and associations with professional and personal demographics. Results On a Rank Order Scale, responses for what constitutes "reasonable suspicion" ranged from requiring that abuse be "the" most likely cause (8 %) of an injury, to the second most likely (9 %), third (18 %), fourth (18 %), to even the seventh (8 %) or eighth (5 %) most likely cause of an injury. On a numerical probability scale, 21 % of respondents indicated that "abuse" would need to be [greater than or equal to] 83 % likely before reasonable suspicion existed; 40 % stated that a likelihood between 53-82 % was needed; 27 % identified the necessary likelihood between 33-52 %; and 12 % set a threshold between 1-32 %. Conclusions The present finding that no consensus exists for interpreting "reasonable suspicion" suggests that a broadly accepted interpretive framework is needed in order to help prepare childcare providers to know when to report suspected abuse. (author abstract)