The field experiments were conducted during 2015-16 and 2016-17 at Norman E. Borlaug Crop Research Center, Pantnagar G.B Pant University of Agriculture & Technology, Pantnagar, U.S. Nagar (Uttarakhand) India, to study the crop intensification and establishment techniques influence on weed dynamics under irrigated rice-wheat system. In Kharif season, density of total weeds as well as grasses, broad-leaved weeds and sedges was observed lowest in rice – wheat cropping system. Transplanted rice-vegatable pea- groundnut cropping sequence proved superior over those cropping systems where upland direct-seeded rice was included as one of the crop with respect to control of Kharif season weeds. In Rabi season, maize (B) (cob + fodder) + cowpea (B) + Sesbania (F)-2:1:2 - vegetable pea (B) + toria (F)-3:1 – groundnut (B) + mentha (F)-3:1(BBF 105 x 30 cm)] proved to be the most prominent cropping system for controlling broad-leaved weeds and sedges. All the cropping systems proved superior for the control of grassy weeds (Phalaris minor and Avena fatua) in which there was inclusion of either legumes or oilseed crops in place of wheat. During summer season, soybean (B) + rice (DSR) (F)-2:1 – wheat (B) + mentha (F) (3:1) - continue (NBS 60 x 30 cm) cropping system was found better for the control of complex weed flora