Internal Models are as necessary as they are problematic. They enable insurers to capture and manage complex risks, yet remain vulnerable to misinterpretation and misuse. The more complex the model the more vulnerable it can become. In November 2014 research conducted by Solvency II Wire revealed that approximately 175 insurance and reinsurance entities across Europe were in pre-application for a Solvency II internal model or a partial internal model. Survey participants, mostly National Competent Authorities (NCAs), were also asked what they considered to be the biggest challenges for insurers preparing for an internal model. They identified four broad themes: handling the volume of work and amount of documentation; ensuring data quality; applying the use test; and adapting the model to local specificities.