And Penelope makes four!

Kourtney Kardashian introduces adorable daughter Penelope Scotland Disick --  -- with pages of exclusive photos -- in the new issue of Us Weekly, out now.

Born July 8 at Cedars-Sinai Medical Center in Los Angeles and weighing 7 pounds, 14 ounces, Penelope joins big brother Mason, Kardashian's first child with Scott Disick, her boyfriend of six years.

Gushes the ecstatic second-time mom (who shares her new Us Weekly cover with sleepy Penelope and a beaming Mason): "Nothing could prepare me for how hard I fell in love with her."

In the new issue, the reality star, 33, and Disick, 29, open up to Us about Penelope's delivery (with the entire Kardashian-Jenner family in tow!), how Mason is adjusting to big-brotherhood, Kourtney's push present, why Disick's afraid to change Penelope's diaper and much more!

Pick up the new Us Weekly for all the exclusive photos and details, on stands Friday!