Ciao Tia, it depends on the importance that it has in the sentence: normally it is used to describe a noun so it is after, like "un ragazzo italiano". If you want to make it closer to the noun, as if this quality (grande) was not just to describe but to define it, you will put it before: "lui è un grande amico" you can listen to this sentence about someone you already know as a friend of him/her (speaking), but he/her wants to tell you how dear/loyal/great is he! As reconfirmation: In the first case if you split the sentence, it won't mean anything this context: "Lui è un grande ed è un amico" (it won't mean that he is great because he is a good friend but just that he is both a great person and a friend) In the second case, you should split "Lui è un ragazzo ed è italiano" this are two qualities that are not linked each other, so it works! I hope I 've been clear! It is a hard topic in grammar!

Examples: - un grande libro : a great book - un libro grande: a big book - un grande uomo : a great man - un uomo grande: a big man - un vecchio amico: Somebody I have been friend with since a long time ago - un amico vecchio: A friend who is an old person. - un bravo ragazzo: a good boy (as a moral quality) - un ragazzo bravo in matematica: a boy who is clever in maths. (intellectual quality) - un ragazzo bravo in XYZ: a boy who is clever in the subject 'XYZ'. (intellectual or physical qualities involved) - il mio caro architetto: an architect who is dear to me - un architetto molto caro: an architect whose work is rather expensive (/molto/ is optional) Usually the adjective follows the noun (rule 1), and if it is in front of the noun, either it is one the exceptions to rule 1, OR the adjective changes its usual meaning (rule 2), for a related but different meaning, which usually (rule 3) is an abstract meaning or a meaning related to an intrinsic quality. It is better to learn this topic following sound examples. E' meglio imparare questo argomento seguendo degli esempi validi. Queste tre regole sembrano semplici, ma occorrono molti esempi per poterle mettere in pratica.