Wife wants a carry gun. She's not too fond of the old S&W 39 I've given her. She wants something brand-new. Something small enough to fit in a purse or diaper-bag, reliable, easy to use, and preferrably in 9mm. Any recommendations?

Glock 26 with a good pocket holster.

Sig-225

ARH

HK USP Compact Stainless Steel 9mm

I got my girlfriend a Colt Gov't. model .380, it shoots great, recoil is barely more than a .22, it's REAL concealable. If larger caliber is desired, I recently bought a Sig P239 (they come in 9mm and .40S&W).  It's a bit heavier and larger than the Colt .380, but still small enough to be concealed easily. And jeez, does it shoot! Glad you're arming her-I don't worry about ANYWHERE my GF goes. She'll shove that pistol in some perp's face in a NY minute-in fact, she already has TWICE. No shots fired, perps running away like scalded dogs.

diaper bag of large purse:


if you want to go smaller take her to a gun show and se what fits her hand.
then take her to a range that rents pistols and let her shoot about a dozen.  

or just buy guns you want and if she does not want to shoot them get another.

lots of ladies (some even with small hands) like a compact 1911.  
try a

personal protection devises should be carried on the body not in a purse or bag.  that way you have complete control of the weapon and if the bad guy steals the purse you haven't armed him.  Also if she has to run she can ditch the purse and diaper bag, grab the baby and haul ass.