Amazon has plenty of 40th birthday decorations to transform your backyard or local bar into party central, plus invitations, party favors, and everything else you'll need. Shop Now.

Shop our guide to the best 40th birthday gift ideas from Alo Yoga, Nespresso, and more. Make her feel special with these editor-vetted picks.

Teddi Mellencamp celebrated her 40th birthday in Mexico with husband Edwin Arroyave and former "RHOBH" co-stars Lisa Rinna and Kyle Richards.