Ancillary services are required to maintain the unity, stability, and quality of power systems. In Colombia these services are required to operate the national power system and the international connections with the neighboring countries. The system is influenced by factors ranging from system's topology to social and political aspects, such as the large number of terrorist attacks. In light of these particularities, we consider Colombia as a learning lab for ancillary services in the region. Colombia's power system relies on three ancillary services for its operation, namely frequency regulation, voltage control, and blackstart service. From 2010 Special Protection Systems were also added. In this paper we first analyze the technical aspects, operational restrictions, financial management, and the most relevant regulatory conditions of these ancillary services of the SIN. We also take into consideration the main regulatory characteristics and statistical data related to energy exchanges that have taken place between Colombia and Venezuela and Ecuador. Thereafter, we depict the main weaknesses and policy challenges that Colombia must address in order to increase the effectiveness and coverage of ancillary services in both the SIN and in the international interconnections. Finally, we propose new market oriented regulations to encourage investments and new tools for international connections. (C) 2012 Elsevier Ltd. All rights reserved.