Langenscheidt has language-to-language dictionaries in many languages, including English, German, French, Spanish, Italian, Dutch, Swedish, Greek, Ancient Greek, Latin, Arabic, Chinese and Croatian, and in varying sizes, ranging from small travel pocket dictionaries to large desk sized ones.

These learning materials became very popular and were widely read so much so that even today, Langenscheidt can be considered the "Father of distance education".

From 1869 Langenscheidt worked with Karl Sachs and Césaire Villatte on the Encyklopädisches französisch-deutsches und deutsch-französisches Wörterbuch ("Encyclopedic French-German and German-French dictionary") and published it in 1880.

In 1891, in close collaboration with Eduard Muret and Daniel Sanders, he started working on the English equivalent, the Encyklopädisches englisch-deutsches und deutsch-englisches Wörterbuch ("Encyclopedic English-German and German-English dictionary").

Most pocket dictionaries include around 55,000 references designed for tourists or people studying beginning or intermediate foreign languages, while larger desk sized interlanguage dictionaries include around 220,000 references.