for us, it was P2. No more "building the foundation" kind of medchem/biochem classes. You jump into the real meat of pharmacy stuff, PK, pharmacotherapeutics, pharmacology, ect. People went from weekend partier in P1 to basically no life. PK was especially tough on many of the girls who got into college by memorize their way through their classes... well that doesn't work in PK. Some cried their eyes out because getting C- means you flunk for a year.