The present study is devoted to measuring speech entrainment between interlocutors of varying social distance based on their vowels’ characteristics. 5 degrees of social distance were taken into consideration: siblings, friends, strangers of same and opposite gender, and strangers of significantly different age and social status. Speaker-dependent acoustic models of cardinal Russian vowels /i/, /a/, and /u/ were constructed and compared. We hypothesized that entrainment would be the strongest between siblings and decrease with increasing social distance. However, it was found that while entrainment is indeed strong for siblings, friends actually show less entrainment than strangers. Same-gender pairs showed stronger entrainment than opposite-gender pairs. Entrainment was also found to be vowel-dependent, with /a/ exhibiting the most variation.