A method of assembling a slider window assembly for a vehicle includes providing at least one fixed window panel defining an opening with an upper frame portion and a lower frame portion fixed relative to the fixed window panel. A movable window panel is loaded at the upper and lower frame portions by (i) inserting a lower portion of the movable window panel into a portion of a lower channel element of the lower frame portion to a first depth, (ii) aligning an upper portion of the movable window panel with an upper channel of the upper frame portion, (iii) raising the movable window panel so that the upper portion is at least partially received in the upper channel and the lower portion is at a second depth to generally align with a receiving portion of the guide element, and (iv) moving the lower portion into the guide element.