Markku Kulmala, Pertti Hari and colleagues in APFE Group started the SMEAR II station in 1995, with an extensive range of measurement interests. The station is situated in a 47-year-old (in 2009) Scots pine stand. It has several operation units to reach into and above the stand canopy: a 128 m high tower for atmospheric and flux measurements, one 18 m tower for irradiation and flux measurements, another for tree physiology measurements and 35 m walk-up tower for aerosol measurements. We perform soil and soil-water measurements on two water catchment areas. In the vicinity of the station we measure solar irradiance from 280 to 800 nm with a radio spectrometer. Some 50 to 100 people are involved in the research carried out at the stations, and they produce about 50 peer-reviewed papers annually. The station has been involved in more than 10 EU projects.