My son is 14 now, with dyslexia and dysgraphia. About two years ago, he asked for help improving his illegible handwriting. He also had never been taught cursive in school (which is ridiculous!!). He's always had terrible handwriting, but we focussed on reading intervention and ignored writing because it would have seemed just too punitive to do both. I bought Handwriting Without Tears, and another book that received 5 stars on Amazon. He worked on it periodically over a summer. He can now write cursive, and wrote me a lovely cursive letter for Christmas! He's still slow at it, but he can write legibly and it doesn't take him too awfully long to write longhand. I think we'll go back to his 504, which allows him to write on a computer, when he takes AP classes. I'd say if your son is ASKING for help improving, get one of the handwriting books and see if he wants to do it on his own and if he wants help remembering to do it regularly. If he's motivated, he'll probably just do it himself.
