Large items:
□ backpack
□ smaller summit pack (if desired)
□ sleeping bag (down or synthetic, to 30° F at least)
□ sleeping pad (closed-cell foam or thermarest style)
□ ski poles (if desired; especially if you have bad knees)
□ hiking boots (any kind)
□ tent (3-season is OK; with rainfly)
 
Items to share with your tent-partner or friends:
□ backpacking stove
□ fuel
□ matches/lighter
□ cooking pot (aluminum is better than steel or titanium)
□ appropriate cooking utensils (e.g. spatula)
□ food for dinner and breakfast
 
Clothing:
□ long underwear, top and bottom (light-weight)
□ socks (e.g. polypro liner and wool outer-sock)
□ pants (nylon quick-drying zip-off pants are very popular)
□ wind-pants (if desired), either nylon or Gore-Tex style
□ gaiters (if you have them)
□ upper layers (e.g. fleece or wool jacket) 
□ shell jacket (Gore-Tex style is nice, but not essential; nylon will do)
□ down jacket (if you have it; very nice to have in camp)
□ hat (wool or fleece)
□ gloves/mittens (I bring several pairs)
□ balaclava/scarf/neck-gaiter (if it’s really windy or cold)
□ sun-hat (for approach)
 
Personal items:
□ utensils and eating gear: spoon, bowl, mug, sharp knife
□ food for yourself: lunch, snacks
□ water bottles (2 quarts minimum, 4 quarts maximum)
□ sunscreen (especially if we’re walking over snow)
□ chapstick with a SPF (especially if we’re walking over snow)
□ watch (for an alarm in the morning)
□ flashlight (preferably headlamp)
□ extra batteries (unless your batteries are 100% new)
□ camera (if desired)
□ small first-aid kit (ibuprofen, gauze, band-aids)
□ moleskin/athletic-tape or similar (for blisters)
□ toilet paper
□ WAG bag (these are forest service provided bags that contain a bit of kitty-litter that you defecate into)
□ Toiletries (e.g. contact solution, toothbrush/toothpaste)