I agree with Tracey, sometimes the pressure is on single mums (I'm one too) to be all mumsy and nice because of stereotyping so we fall into problems with discipline and listen to too much pyschobabble about being nice about EVERYTHING which then backfires on us. And then even with the most loving ex, they don't see it as much as we do so we don't have there back up. Don't be afraid of being firm, and don't look on it as a single parent problem, lots of kids go through phases like this with two parents living with them. Try to predict situations as much as possible and distract from them before it reaches the hitting point and provide stuff that can be whacked without consequence so she has an outlet for that desire, not whacking stuff thats the problem its whats getting whacked that matters! If she does hit someone have a definite consequence for it to make it a less appealing thing to do. My son is 3 and will roar very loudly like a tiger at anyone passing, most people take it very well but a few older people have had nasty shocks, so your not alone in your problem.