Jack Osbourne's Wife Files for Divorce

Jack Osbourne's wife is calling it quits -- she's filed for divorce after 5 and a half years of marriage, and on the heels of expanding their family.

Lisa Osbourne filed divorce docs Friday in L.A. County. The couple just had their third child in February -- a girl named Minnie Theodora. They have 2 other girls, ages 6 and 2.

According to the docs, obtained by TMZ, she lists the date of separation as May 4. Jack was already ring-less Friday while out and about in L.A.

Lisa's asking for joint and legal custody of their children. She also wants spousal support, and Jack to foot the bill for her attorney.

Jack and Lisa got married in October 2012 with a small ceremony of less than 50 guests in Hawaii. He popped the question to the model after just 4 months of dating..