Abstract: Various embodiments provide for the creation and validation of resource templates that may be used to provision or launch resources or resource instances. In various embodiments, a user can use values for various resource instance parameters to create a resource template, and can request validation of that template. A validation service can perform multiple validations, including independent validation of all template parameters, as well as validations of cross-parameter dependencies. If any errors are detected that cause the template to be invalid, information for those errors can be returned to the user such that the user can make the appropriate changes to enable the template to be valid. Templates can be re-validated at future times, such as at launch time or for use with a new service, to ensure the template remains valid under those circumstances.