|Publisher||Foreign Service Institute|
The Foreign Service Institute's ("FSI") Foreign Language Institute developed a series of language courses to help train American diplomats before they were stationed overseas. There are three main program types: the Basic, the Programmatic and the START courses. All of them are centered around repeated drills that are designed to promote overlearning of the material.
The Basic courses are the most comprehensive. Their lengths can vary, ranging from ten units to one hundred and twenty. There are Basic courses for a huge number of languages as well, including many African and Asian languages that have few other resources. Two of the largest are Mandarin Chinese and Swahili.
Since they were developed by the government, many of the courses are now in the public domain. The Foreign Service Institute Language Courses website has posted many of the available languages on the Internet, and they can be downloaded for free. Most courses are also available here. Unfortunately, for some major languages, such as Russian and Japanese, the courses used by Foreign Service Institute were copyrighted by their developers, and are not available in the public domain.
General consensus on HTLAL is that these courses are very efficient but also boring for many learners. An example of the less boring ones could be FSI Swedish which is generally considered to be a wonderful resource.
Some of the courses no longer provide you with the up to date correct orthography due to reforms, such as the German one. In such cases, it is recommended to either supplement FSI with another resource or to not care if you are unlikely to encounter situation in which you would need absolutely correct orthography, such as international exams.
Even if you are not fan of the grammar drills, the phonetic ones at the beginning are well worth it as they'll introduce you to many examples on all the pronunciation rules and you are given enough material to practice on.