Proof of residency (for schools)
If you don't have children this might not apply, but you will need a proof of residency document - Empadronmiento or Padron - before you can use education services
Second thing we thought we needed to do was the school. But to do this you need a proof of address paper. The proof of address paper is something you get from the district area offices from one of the Barcelona district offices (note this isn't the residency card). What they do is look at your property contract and duly stamp a certificate to say you live in a certain district in the city. By the way, it isn't clear if this is needed if you're not using schools or local facilities.
So here we are on a paper hash. Literally involved taking one pile of papers from one office to another, an official checking our paperwork and providing us with a stamped certificate to say we were residents which we then had to walk to the school office (along with things like birth certificates) to prove we were resident and that we had children needing school places. One thing we learnt quickly is that if you have the papers everyone is hugely friendly and helpful. Without the papers they won't really talk to you. There are a few more wrinkles for schools which probably won't affect anyone else.
If you are interested, the education office is in Bruc, you can actually get the proof of residency from any of the district offices. So from Bruc the closest is actually at the top of the street for Eixample. You don't have to go to your neighbourhood office (if we'd known this on visit one we would have managed the education department in less than 5 goes).