Abstract: A lineage-based trust for machine images that are derived from another may be established to validate a machine within the lineage before it is used to launch a virtual machine. An offspring machine image may be derived from a parent machine image through modifications made to the parent machine. Further, an integrity metric may be computed for each such modification and a data structure may be provided through which the parent and offspring machine images can be linked. When a customer of a provider network requests a virtual machine to be launched using a specified machine image, the specified machine image is loaded on to a host computer and validated using the associated integrity metrics before the virtual machine is launched.