The overrepresentation of Aboriginal children in child welfare systems in the U.S., Canada, and Australia is well documented, but limited attention has been paid to investigation-stage disproportionality. This paper examines the overrepresentation of First Nations the largest of three federally recognized Aboriginal groups in Canada children, focusing on three questions: 1. What is the level/nature of First Nations overrepresentation at the investigation stage? 2. What is known about the source of referrals in child welfare investigations involving First Nations children? 3. What risk factors and child functioning concerns are identified for investigated First Nations children and families? The First Nations Component of the Canadian Incidence Study of Reported Child Abuse and Neglect FNCIS-2008 was designed to address limitations in existing Aboriginal child welfare data: it sampled one quarter of the Aboriginally governed child welfare agencies that conduct investigations in Canada, gathered data on over 3,000 investigations involving First Nations children, and incorporated weights designed for analysis of First Nations data. Bivariate analyses are used to compare investigations involving First Nations and non-Aboriginal children. The rate of investigations for First Nations children living in the areas served by sampled agencies was 4.2 times that for non-Aboriginal children; investigation-stage overrepresentation was compounded by each short term case disposition examined. A higher proportion of First Nations than non-Aboriginal investigations involved non-professional referrals, a pattern consistent with disparities in access to alternative services. Workers expressed concerns about multiple caregiver risk factor concerns for more than 1/2 of investigated First Nations families and, with the exception of health issues, identified every caregiver/household risk factor examined in a greater percentage of First Nations than non-Aboriginal households. It would be extremely difficult to reduce First Nations overrepresentation at later decision points without addressing overrepresentation at the investigation-stage. Despite the serious needs of investigated First Nations families, alternatives to traditional child protection responses may be appropriate in many cases. If First Nations overrepresentation is to be reduced, child welfare agencies must be equipped to provide supports needed to help families address factors such as poverty, substance abuse, domestic violence, and lack of social supports.