A 16-day Mahalakshmi Vrata, or Solah Din Mahalaxmi Vrat, is observed in
North India in the Bhadrapad Month (August – September). It begins on the eighth day of Shukla Paksha (waxing phase of moon) in Bhadra Mahina and ends on the Ashtami day of waning phase of moon (Krishna Paksha) in Ashwin month. Mahalakshmi Vrata 2011 (dates) begins on on September 5 and ends on September 20.
The popular belief is that one will get back all the lost material wealth by observing Mahalakshmi Vrata. People also observe it for attaining peace and prosperity.
An important ritual during the period is the tying of a sacred thread having sixteen knots.
People avoid non-vegetarian food during the period.
A Kalash or Purna Kumbha symbolizing Mahalakshmi is worshipped on the last day of the Vrata.
You can get more details of the 16-day Mahalakshmi Vrata in
North India in this article.