with the behavior you model.  Spoiled, bratty parents tend to have spoiled, bratty kids.  I know this isn't behavior that you indulge in, so its unlikely your daughter is going to turn out that way.

That said, I am not one for punishment.  I have certain expectations, but I've found that at young ages, kids are very interested in hearing the "whys" concerning behavioral rules.  And always, the fall back question to ask is "would you like it if I treated you this way?"  

I'm not that much ahead of you (my oldest is 4.5) but I do agree that discipline (I like to think of it as "guidance") is really important when they are young too.

The trick for me is picking my battles.  Like you, I've decided that food is not going to be a battle.  I make dinner, you don't eat it, that's fine.  I don't offer a million things though, just because what I have served is rejected.  We just move on and wait for the next meal or snack.

Throwing things, not listening to me, backtalking, all of that is unacceptable so for that I do try to guide a little more firmly, maybe do a timeout etc.

It's tough!

My oldest was a lot like this when she was 3 (and 4 and 5!). She would wake up screaming, go to bed screaming and scream much of the day in between. It was frustrating to say the least. Let's just say she wasn't the only one screaming! ;)

Now that she is older (8), and I "know her" better, there are a few things I wish I'd realized about her back then. Maybe these apply to your DD?

• She is VERY physical. Now, when she is upset, acting in appropriately or just struggling with her homework, I send her outside to run around the house five times. She loves it, and the change it effects on her state of mind is remarkable. If I'd known that when she was little, we would have played a lot more tag! If I could go back to the dinner table when she was 3, I would definitely make her do 30 jumping jacks before she sat down to eat.
• When she throws tantrums (she is still very emotional), she feels really out of control and it's scary for her. When I see them coming, I try to head them off with hugs and deep breaths and diversions. I always try to be there for her afterward, and I try to talk about how she's feeling.
• One big trigger for her is fear of the unknown (which can be as simple as "what will that taste like?" or as complicated as "what will life be like when I'm a grown up?"), so I try to prepare her for unusual circumstances. Some phrases that might work at dinner are: "This tastes like chicken," or "You already tried that once and you liked it" or "Little girls who cooperate with Mommy at dinner get an extra bedtime story!" (There's nothing like wholesale bribery.)
• While we're on the food issue, DD was a healthy, but picky, eater. She doesn't like meat or dairy, which made mealtimes kind of difficult when she was small. Now we let her "trade" one healthy food for another. Since she's never met a veggie she didn't like, she will trade her pork for more squash, etc. It acknowledges her own personal (and I believe legitimate) preferences, gives her control over her own eating habits, and encourages her to explore the idea of healthy and balanced eating. We could have started that earlier, I think.
• You are right to address her discipline issues--even though it's exhausting and sometimes feels terrible. I always made a point to deal with DD's inappropriate behavior in some way--whether it was a stern talking to, taking away a toy or activity, or just putting her in her room while she screamed it out. I always tried to give ample warning and follow through on those warnings. Now when I say "stop that, or else _" she believes me the first time, and I think all those frustrating yeras were worth it. She's also a swell kid in general, and I think she is learning to channel her passionate nature in more positive ways.

I thought 3-4 was a really tough age. There are some things I would do differently, but I wouldn't go back and 'let her off the hook." I do think with her strong personality she could have become very bratty.

Wow, this was long winded! Thank you for the trip down memory lane! As I imagine your little sassypants, I have a smile on my face. I'm sure she's going to grow up splendidly!

They're so frustrated by everything and they're just big balls of energy.  I guess it's hard for them but it made me mental each time I had a three year old.  Basically I just got through it by repeating "it's a phase, it will pass, it's a phase, it will pass"  and it did.  

My advice?  Just hang on tight...4 is coming...

My son will be four in December.  He was the tantrum king right around when he turned three.  It lasted a few months and then he was back to normal until recently.  Now he's a little tantrumy again but not as intense as when he was a new three.  I've noticed that there are some times of day that are really bad for him so we don't ask too much of him at those times.

On the being rude, defiant etc.  I agree that there need to be consequences for those actions/behaviors or he will not be well socialized.  DH and I experimented with that.  Time outs were not terribly effective as sometimes he would do something he knew was naughty and then go to his time-out chair like he planned it out in advance and knew the consequence and decided he could live with it.  

What works best with him is putting toys in time-out.  We usually give him a warning if he's starting to act out but if he does something really, really bad all of his Thomas trains go up on top of the refrigerator and stay in time-out until he earns them back with good behavior.  We had one pretty bad day where all of his Thomas toys, Bob the Builder trucks, and other various trucks ended up in high spots.  He takes the  threat of toys in time out very seriously and usually cleans up his act.

We're dealing with them on a daily basis as well, with our almost 4 1/2 year old.  It's a good thing that he is cute when he sleeps, since he's not always real cute when he is awake.  

For the most part, we understand the developmental part of it all and realize that this shall pass.  But it requires a lot of teamwork on our parts and we're never afraid to tag team when one of us has had it.  I am so grateful that DH works next door or from home so he is available.  

We have found two things that work:

1.  Ignoring.  Last night, he followed me around and I just kept at my business despite his shouting and demands.  A few weeks ago I would have redirected him and ended up in his room with him on time out.  But by ignoring him, he wasn't getting what he wanted by taking nasty to me, which was my attention.  It was kind of amusing to watch him trying to pick a fight when I wasn't taking the bait.  He settled down pretty quickly.

2.  Staying calm.  Ignoring is so much easier to do when I am calm.  Even when my voice is calm, I am learning that Little Boy knows when I am jacked up and it keeps him escalated as well.  I am working very, very hard at mentally reminding myself to be calm and not let him see me out of control.  We keep a stack of magazines handy so that when we are in his room, keeping watch over his tantrum (we have to for safety reasons) I can at least look at the pictures in the magazines rather than look at him - and this helps me stay calm.

Oh, and have a sense of humor.  This morning, Little Boy was in his grumpy place and was yelling for my husband and I.  When simply yelling our names didn't work, he said this:  "I am giving you to the count of 3 to help me.  1.  2.   3."  I couldn't help but laugh!

that the new sibling is really traumatic for her. My oldest acquired his baby brother when he was 2 yrs 8 mths--and then we moved two months later. Poor thing basically lost his center-of-the-world status and his home all in one go. It took a long time for him to settle down. I think consistency and patience is the best you can aim for.

As to dinner, you are doing the right thing. The usual advice is to serve one meal for everyone, but make sure you offer a few options within that (for instance, chicken with or without the scary sauce). And everything is optional. If the meal is chicken, scary sauce, pasta, and veggies, let her pick what of that she wants. Don't comment or cajole or plead or demand. Just serve what she asks for and let her eat it. If she doesn't want to eat anything, that's ok too--as long as she knows she can't go get something else from the fridge and no, you won't fix her anything else until the next mealtime (I always offered milk and cheese at bedtime, but nothing before then). Finally, always serve something like bread and milk with dinner, so if she really is hungry but doesn't like what you served, she has a neutral option.

If you're really worried about eating habits, check out "How to Get Your Kid to Eat, But Not Too Much," by Ellyn Satter.

Kids tend to have acting out phases right around their "half" birthdays-- like clockwork it has happened to Liza for the past 8 years ....

the other thing I have learned is to remove MYSELF frmo her when she gets on my last nerve... to keep my voice low and calm, to come down to her level, to look her in the eye and to just keep repeating what I need to say.  

does it always work? of course not. Am I a lot calmer --oh yeah.

doubt you'll raise a brat.  The fact that you are conscientious about her behavior will keep that from happening.  I've read through the comments about age 3 being tough.  All I can say, is all kids are different.  For both my kids, it was (and is for my daughter) the tough age.  Sure we had some temper tantrums at 3, but now we get "Why not" and then I have to try and explain why you can't have your friend from preschool over every single day.  And sleep issues are coming up too... bedtime has become somewhat of a power struggle some nights.  Like others have said... it'll pass.

As a friend once told me, it's their job to be difficult.  They are testing their environments, limits, all those things.  It's all part of the growth process and completely normal.  Here's some information about temper tantrums from Peggy O'Mara's Book Natural Family Living:

Recognize that temper tantrums are a normal, healthy, necessary release for toddlers and that you can do nothing to control them.  Young children lack the verbal skills or cognitive awareness to interpret the powerful emotions they fell, and sometimes fear, anger, or frustration explode in a very physical way.  A no-holds-barred tantrum can be very cleansing to a child, who will usually emerge calm and renewed.

A tantrum is as overwhelming to the child experiencing it as it is to adults witnessing it.  The best thing you can do for your child when he is in the midst of a full-blown tantrum is to stand by quietly and give him the time and space to work out his rage.  If you are in a public place, you may have to remove him to a place where he won't disturb others.  Instead of shutting him in a room by himself, stay with him until his fury subsides, so that he can climb onto your lap, be comforted, and then get on with the business of learning about the world in a trusting, open way.

She's right... tantrums are overwhelming to the parents as well.  I find that if I'm calm, my kids calm down faster.  If I can let go of the situation and not take it personally, things usually go smoother.  

Some folks have mentioned books... I love books by Faber & Mazlish like How to Talk to Kids so That Kids Will Listen and Listen so Kids Will Talk.
Also, Raising Your Spirited Child by Mary Sheedy Kurcinca is helpful if you feel your child is especially "spirited".  And finally, we will be doing a book discussion on Kurcinca's book Sleepless in America on the 22nd.  I've just gotten the book and skimmed through.  It looks like a lot of behavior problems could to tied to lack of sleep.  If this sounds like you child, you may check that book out too.

Best of luck to you as you navigate this wonderful and trying time with your child.  :-).

and it happened very much at the same age with my dd.  now we didn't have a new baby in the house which i am sure complicates the whole situation.

here's what i found that worked and used throughout childhood with dd.  i would see her wind up and notice increasing frequency of temper tantrums, back talking and in general lack of cooperation. as i saw it rise i would calmly let her know that it was time for us to make time to have a "discussionation".  i would formally sit her down in living room and lay out what i was seeing, get her agreement and then tell her what needed to change specifically.  we would indeed discuss it and then agreement to get it in order and then end with a hug.

every 3 to 4 months she'd wind up again and we'd have the formal discussion.
seemed to work from @ age 4 forward.

there are others going through the same thing. DD is 4.5 and I swear the last couple of months she's become unrecognizable. I now count the days when there wasn't a tantrum - very few and far between lately. We never know what's going to set her off. Last week, she decided she was no longer going to wipe after using the bathroom... just because she felt like it. WTH? DH tried explain the importance, blah blah blah, then the screaming started and all was lost. she was brought upstairs kicking and screaming for a time out.

I've tried the toy time out and she just doesn't care after awhile. Same with losing a play date. Between her fits and my 2 year son testing his will power/bravery/stubbornness we're just wrecked.