The LLAMA Language Aptitude Tests (Meara 2005) are a set of exploratory tests designed to assess aptitude for second language (L2) learning. In its current or earlier version (i.e. the LLAMA or LAT), this battery of four subtests has been used in an increasing number of studies in the second language acquisition field. However, as indicated by Meara, it has not been extensively standardized. This chapter reports on the results of an exploratory validation study that assessed the reliability of the test and explored its underlying structure with a sample of 186 participants. The results showed that internal consistency and stability in time were acceptable. A series of exploratory factor analyses further suggested that the test is measuring two different aptitude dimensions.