The Khalkha dialect (Mongolian script: Qalq-a ayalγu, Mongolian Cyrillic: Халх аялгуу Khalkh ayalguu) is a dialect of Mongolian widely spoken in Mongolia and according to some classifications includes such South Mongolian varieties such as Shiliin gol, Ulaanchab and Sönid. As it was the basis for the Cyrillic orthography of Mongolian, it is de facto the national language of Mongolia. The name of the dialect is related to the name of the Khalkha tribe and the Khalkha river.

The Mongolian language (in Mongolian script: , ; in Mongolian Cyrillic: , ) is the official language of Mongolia and largest-known member of the Mongolic language family. The number of speakers across all its dialects may be 10 million, including the vast majority of the residents of Mongolia and many of the Mongolian residents of the Inner Mongolia Autonomous Region. In Mongolia, the Khalkha dialect, written in Cyrillic (and at times in Latin for social networking), is predominant, while in Inner Mongolia, the language is dialectally more diverse and is written in the traditional Mongolian script. In the discussion of grammar to follow, the variety of Mongolian treated is Standard Khalkha Mongolian (i.e., the standard written language as formalized in the writing conventions and in the school grammar), but much of what is to be said is also valid for vernacular (spoken) Khalkha and other Mongolian dialects, especially Chakhar.