Outsourcing is a management strategy where total or partial activities are assigned to external individuals or firms to avoid costs and enhance quality. This research presents a model for selecting among providers for maintenance activities based on technical and commercial criteria. To this end, literature and experts were consulted to obtain and verify the importance of each selection criteria. Service providers (contractors) are then assessed based on the various criteria and the provider (contractor) with the better overall score is selected. The research utilizes Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for its reported flexibility and relative accuracy. The proposed model was applied to select among maintenance service providers in a cranes industry based on contractor's ability to provide a service of acceptable standard, on time, and within budget.