How Old Do Children Have to Be Before They Understand Discipline?

Cause and effect.
This is the basic sense that most kids can grasp.
At that young age.

As for UNDERSTANDING discipline and all the intellectual abstraction of it and to have TOTAL mastery over impulse-control... well certainly not a 15 month old.
At this age, developmentally, they do NOT even have "fully developed" impulse control.

Every "expectation", of a parent, has to be age-appropriate.
Otherwise, the child.. and then the parent, will be continually disappointed or frustrated.

Discipline in it's original meaning of teaching or training, babies get from birth, by imitating (as well as they can) the examples they see and hear.

Discipline in the sense of punishing for wrongdoing, they begin to understand around 1.5 years or so. Before then, they will merely be learning to avoid pain, but won't really understand the meaning of right and wrong. They are very immediate in their needs, and have not yet achieved the brain development needed for consistent impulse control.

My ex-in laws both wore glasses and by 3 months the kids and grandkids learned not to grab at their glasses. They would tap the baby's hands with a finger and say 'no', I couldn't believe it worked.
As far as your daughter goes, she needs to learn to mind but don't break her spirit. She is that strong for a reason. Someday she will need all the strength and toughness she has. There is a master plan, you just gotta have faith.

My son didnt really start getting consequences until about 20 months.

Even my doctor, who I describe as "old school" said not to waste time with time outs, etc at the 18 month appointment because they dont really get it yet.

We did ALOT of redirecting at this age. Also, instead of saying "no" so much, we tried to say what TO do. Instead of "Don't go out the door" Say "Stay inside."

Your daughter sons alot like how my son was at that age and it WAS tough. He wouldnt sit in the cart at the grocery store and screamed and yelled. I would be trying to put him in his carseat and he would be having such a crazy fit that people would look at me like I was abusing him. It wasnt an option to NOT ride in the carseat and no cutesy trick worked, so I just wrestled him in. It was NO FUN! Around 20 months, he started getting better as he started getting consequences (If you yell in the store, we are leaving, and you wont get an orange...) and as he started to talk and be able to express himself more, he got better.

Now he is almost three and is still strong willed, but he gets consequences. If I tell him to do something, and he doesnt do it by the time I count to three, there is a consequence. MOST of the time he does it.

My advice:
1) If you say no, redirect after. "No, dont touch the oven. Ovens get hot. Ouch. Play with this toy instead."
2) Use a positive instead of a negative. "Play in our yard." instead of "Dont go to the neighbors yard."
3) Have an escape plan. Always be able to remove her from a store or restaurant immediately if her behavior is not good. If you have to get groceries, have a friend or family member go with you who can take her to the car if she acts up or go alone.
4) Accept that sometimes you are just going to have to wrestle - its not an option to have no diaper and know that eventually she will get better. Just think, when she is 13 she would be mortified to leave the house with no clothes. You wont have that battle to fight then... :)

I read a study that children do not have the developmental capacity to actively weigh a decision and purposefully make a "bad" choice until the age of 5. That does not mean that teaching and inappropriate/unsafe behavior is ok until then, but up to that point it is our role to teach.
I would recommend some child development courses online on discipline and redirect. Also there is a great little newsletter called "Growing Child" it goes up to age three, but provides developmental advice and milestones on your child and even tips on what child is thinking and what you can expect from them. A real life saver for me!
Also, there are some times where you may just have to "give in" if your child doesn't like to lay down to change, change her standing up or on the floor - she is ole enough not to need a changing table. I minimized the "fights" as much as possible for my sanity.
Well, hope that helped a bit. Good luck with your kiddos. they sound like they are in great hands with you!

I really like the "Love and Logic" series.

I agree with Peg and Laurie. I think babies are very smart and very instinctive, they would react to faces and to tone of voice and will follow simple patterns that helps them (like crying and sucking). Before 2, redirecting and even say "no" (and the "eye", lol)worked good for us. My neighbor was amazed when she saw my wonderful white couch with my decorations in the coffee table and that my then year old wouldn't touch. At that point it was as easy as just keep telling her no and redirect, never had a problem. Now that she is 2.5 we do times out when she won't listen to a simple no, and is working fine so far. I haven't yet taking away toys or privileges, but I think that would be our next stop if needed. With both of my kids also "The Eye" worked since young, I think the little one was upset to disappoint me and the older because was a pre of what will come if she continues.

When my children were 15-months, I wasn't focused so much on disciplining them as I was on redirecting them and teaching them what the rules were (example: caught in the act of pulling the kitty's tail, I'd take my daughter's hand and show her how to pet the kitty nicely, and then say, "We pet kitty gently." Teaching the rules and redirecting their attention when necessary was what I spent a lot of time on during their toddler years. After they turned about 2-1/2, they did get time out for anytime that they got physically agressive (hitting, biting) or threw a tantrum.

redirection is probably still your best bet. i remember thinking at this age, "can't i just put him in time out!!" because it got trying, doing it over and over and over - but it's still the best option. if you are firm with your "no" and keep removing the object she's not supposed to have, or removing her from the no-no area or activity, she will learn. she might take longer than your son did :) but it's still consistency consistency consistency. don't give in because that will encourage her and all the work you've done will backslide. you want to be especially firm with her if she is strong willed. you just have to be stronger. if she's throwing a fit don't pick her up, unless it's to put her in her room. tell her that she can scream and cry in her room. it's not allowed in the livingroom, kitchen, etc. she WILL understand that. and soon she'll understand the time out. you'll know. good luck!

When my daughter was newborn and I would hold her in my arms and say NO too abruptly at someone else, her eyes would open. When she turned about 5 months and broke those teeth, I was able to say no while nursing and administer a "time out" from the breast and she learned. So they understand at a very young age.

If your daughter looks at you and smiles - she knows!! We started formal discipline with our twins when they turned one year old. We did time outs and consequences for their behaviors, and we also give very positive, verbal praise when they make good choices. Be cautious of the word "no" unless you want it spit back out at you. We always worded things like, "We don't hit" or "Let's not touch the TV," and such. Basically, if you're asking if she's too young to start now, no, she's not. Start now for more consistent results.

12-18 month old classrooms have kids that follow displine and yours falls in that category. be consistant lay down the rules or you will reap what you sew in the future

When my sister moved in my home with her 3 kids, her youngest was about 1 1/2 yrs old. She was stubborn and wouldn't listen. She was also a screamer if she didn't get her way. Since she was in my care during the day, I would place her back in the crib and close the door every time she screamed or threw a tantrum. She learned that she was missing out and knowing her siblings were out there playing and she wasn't. It took me about a week of consistently taking her out of the situation. I know it will be tough for you but it will be just for a week until she gets it. That she won't get her way no matter what. My niece was also abusive to her older brother but I took away her favorite toy or blanket and gave it back when she played nicely. The key is to be consistent. It's not too young to discipline. Children can manipulate parents and start very young. Always remember you are the parent and teacher of your child.

I didnt read all of ur answers so sorry if this a repeat.
My son who is now 2.5 has been very "spirited" himself since birth. Telling him no is pointless. He is determined, and stubborn, and smart! I've been through hell and back with his tantrums, hitting, biting etc. And like your daughter, when he's happy and sweet he can light up the world! It's a very fine line, and it's been VERY hard.
I have read so many books, asked advice on here MANY MANY times. I finally made my husband and I an appointment w/ a child therapist, and she suggested the book "Parenting with love and Logic" there are many volumes, we have the birth to six years. And FINALLY something is making sense to me! I am hopeful for the first time in a LONG time.
This book recommends "discipline" very early on. Meaning when your baby is old enough to see cause and effect (6-9 months) is when you start. Ex: if you are feeding them, and they start spitting food all over, you calmy say something like " Oh, too bad. Lunch is over" And go sit them in a crib or pack n play for a minute or two. And ALWAYS keep your cool. Which I have been VERY guilty of not being able to do.
I can't recommend this book enough! She knows whats she doing, and shes getting attention so she'll keep doing it! Good luck!

When re-directing isn't enough, I'd say, "no, not nice" or whatever fits the situation, with a gentle, but serious tone and put her in the pack n' play for a few minutes. It's worked well on all 4 of mine. You can do that if she starts fighting you on the changing table too. It might take a few times before she gets it though. My other trick for diaper changing a baby that age that doesn't want to be changed is to let her hold something that I don't usually let her hold, like the tv remote or a calculator or something. I'd try that approach 1st, if you haven't already. Not the phone though- my friend's 18 mo actually dialed 911 once, and they had no idea. They were pretty surprised when the police showed up at the door- lol.
Good luck :)

I started timeouts around 1yrs old with my kids and the kids I babysit. They may not have exactly understood but they quickly learned not to do what I was saying not to do. Some things you just cant remove from them but they need to learn that they cant do it. ex. i had good size yard but there was no fence the kids could not go on the rock driveway that was the boundary I wanted to teach them so I would tell them and walk them away, second time I would move them again and give a warning for timeout, third time was a timeout. Kids learn pretty fast what you will allow them to do but they will also test the limits to see if you really mean what you say. About the diapering why not change her standing up as long as its not a poop. You get the hang of it and its pretty quick and then it can lead you into potty training when the time is right.

My 10 month old listens to me when I tell her no... I don't expect her to remember what I am telling her no for, but I do expect her to stop when I say no. Usually, I use a finger flick and redirection. So if she is trying to climb on the TV stand, I tell her 'NO! Stay down!' and redirect her to a toy. If she goes back right away, I will flick her fingers and tell her the exact same thing, and move her back to her toys again. But she is only 10 months old, so I can't expect her to remember that the TV is off limits. I do the same thing for pretty much everything... No touching, stay down, etc. As far as the diaper thing, I think that's pretty much normal. I have to hold my DD down too... sometimes giving her a toy will keep her distracted long enough for me to change her. If not, I just hold her down and get it done as quick as I can. Consistency is key... If you tell her NO, then let her get away with whatever she is doing, you are just wasting your breath.

Start disciplining her, like yesterday! She is old enough to understand no, and clearly she is already testing boundaries. I would start time outs by placing her in her crib or playpen and then leaving. Come back after a short time or once she is done with her fit. She'll figure out quickly that the fits don't work, and she'll learn to get her emotions under control. My 6 yr old is strongest willed child we have, so I feel your pain!