From Rome or Naples: A1 motorway towards Naples - after the Caserta Sud exit take the A3 motorway towards Salerno until the Castellamare di Stabia exit. Follow the directions for Sorrento up to Piano di Sorrento, where you need to turn for Positano.
Coming from the South you can take the "Costiera Amalfitana" from Vietri sul mare and following the coast and crossing Cetara, Minori, Atrani Amalfi and Praiano, along a rather narrow and winding road among the most suggestive in the world, you arrive in Positano.
From Naples airport reach Sorrento with the Curreri shuttle service and then continue to Positano with the Sita buses that leave from Sorrento station.
From Naples airport with the shuttle service leaving every 10 minutes to reach the central station of Naples where trains leave for Sorrento, then continue to Positano with the buses of the sita.
From Naples airport with the shuttle that leaves every 10 minutes to reach the Molo Beverello port where ferries and hydrofoils leave for Positano.
From the central Naples station trains leave for Sorrento then continue to Positano with the buses of the sita.
From the port of Naples or Sorrento: numerous ferries and hydrofoils.