I'm 6'0 170 lbs with a slim/athletic build. I purchased a size large in Oxblood Red. I purchased a size large because of this jacket's supposed 'trim' fit and because I intended on wearing a fleece mid- layer underneath. First and foremost, the look, quality, and comfort of this jacket are all incredible. Upon first trying it on, it instantly became my new favorite jacket. Now to the sizing issues...For the most part, the jacket fit rather well in the torso/chest region. However, the jacket ran a bit long, and the waist hem was a bit wide/baggy for me. Sure, I could use the drawstring to adjust the waist hem, but it just doesn't look so great when wearing the jacket. Ultimately, I am going to say the jacket fits 'true to size', although I will personally note that it is trim in the torso, wider through the stomach/waist, and is cut long. I intend on returning the jacket for a size medium, but now I am nervous that this new size will be too small...wish me luck!