We are delighted to present the first volume of the Special Issue on Natural Language Processing (NLP) for Similar Languages, Varieties and Dialects. The special issue builds on the success of the series of workshops on NLP for Similar Languages, Varieties and Dialects (VarDial), which have been organized yearly since 2014 and were co-located with top-tier NLP conferences. VarDial has become an important forum for scholars working on a range of topics related to the study of diatopic language variation from a computational perspective.

The success of the VarDial workshop series and the interest of the community in NLP for similar languages, varieties and dialects has motivated us to organize a special issue on this topic. The response by far exceeded our expectations: we received a total of 51 submissions for this special issue. Thus, we split the special issue into two volumes: this one and a later one to be published in 2020. The present volume includes five articles which reflect the diversity of the research on this topic, including language and dialect identification, morphosyntactic tagging and text normalization.

We would like to take this opportunity to express our gratitude to our wonderful guest editorial board members who worked hard to review the unexpectedly large number of submissions we received. The names of all board members are listed on the special issue website.Footnote ^a We further thank the NLE editorial staff who helped us with the preparation of this special issue and who made it possible for us to divide the special issue into two volumes.