Is it permissible for a woman to sit with men in the same place?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

If the men are Mahram (non-marriageable) to the woman, then there is no harm if she sits with them as long as she wears proper clothes that cover the parts that they are not allowed to see from her body, namely, all her body except the face and the limbs according to the preponderant opinion of the scholars.

 However, if there are non-Mahram (marriageable) men, the woman should not sit with them in the same place, as Allaah The Almighty Says (what means): {And when you ask [his wives] for something, ask them from behind a partition.} [Quran 33:53]

‘Uqbah ibn ‘Aamir reported that the Prophet, sallallaahu ‘alayhi wa sallam, said: “Beware of entering upon women.” Thereupon a man from the Ansaar said, "What about [male] in-laws?” The Prophet, sallallaahu ‘alayhi was sallam, replied: "Male in-laws are death.” [Al-Bukhari and Muslim]

In addition, there are many other explicit evidences that forbid gatherings of men and women in the same place.

Allaah Knows best.