Outsourcing has been identified as one of the key factors for improving companies’ financial performance. Moreover, the procurement of business services has become an important element of companies’ acquisition of external resources. However, there is a lack of evidence linking services outsourcing and performance. Limited prior literature has mostly assumed that this relationship is positive and linear. Our empirical study reveals that firms may be able to increase their performance through services outsourcing; however, this is only true up to a point, beyond which the performance decreases as a consequence of further outsourcing. Identifying the type of relationship between the variables under study is a key point to company managers formulating their service outsourcing strategies. They must be aware that there is a level of outsourcing that should not be exceeded. Future research should help managers to determine which is the most effective level of service outsourcing for their companies.