This issue of CTBTO Spectrum focuses on the Latin America and the Caribbean (LAC) geographical region and the CTBT. It is the first issue in a series which will be covering all six Treaty-defined regions. The LAC region has always played an important role in contributing towards ensuring the entry into force and universality of the CTBT. When the Treaty opened for signature in 1996, 21 LAC States signed it. In the meantime, the number of signatures has increased to 27, with 20 LAC countries having also ratified the CTBT as of 6 December 2004.