If you are coming to Italy on work visa or study visa, you have the rights to take your spouse with you.
You need a “nulla osta” (entry clearance certificate from Italy) for taking your wife here in Italy as a family visa.
There are two cases..
1. Taking wife with you at the time of first entry into Italy.
For this purpose, your employer or sponsor needs to apply for “Nulla Osta per Familiare al Seguito” (No Objection certificate for accompanying spouse/minor children) on Behalf of you.
And for this a “Delega” must be signed before this Consulate General to nominate a person in Italy to apply for and obtain the “Nulla Osta per familiare al seguito” on behalf of the principal applicant. Contact your employer for this..., this process takes up to 90 days.
2. Calling you family on family visa after you are settled in Italy.
For this purpose you need to apply for "Nulla osta per Ricongiungimento familiare" once you are here in Italy. This process could also take up to 90 days. But never done in 90 days.
Process one (“Nulla Osta per Familiare al Seguito” ) is with less headache from your side.
3. If both options does not work, then another option is to take your wife with you on toursit visa, But this would be valid only for 90 days only.
Final comment and personal experience:
The Italian Bureaucracy is at high, It is very difficult for a foreigner to deal it with. The average time taken for giving the stay permit “permesso di soggiorno” is around one year, which is around two weeks in Geramny and other EU countries. Some times you receive your expired permit. You have the similar story for the Nulla osta also.