AbstractRice straw cellulosic ethanol fermentation waste (CEFW) and municipal solid waste derived fiber (MSWF) were used as alternative fibers for recycled paper making. The fibers were mixed with old newspaper (ONP) fiber at different mass ratios to produce standard recycled papers and paperboards. A “green” adhesive binder derived from kraft black liquor (BLDB) was used to improve the physical properties of the waste-derived paper products. The values of these properties increased linearly with increasing average fiber lengths, regardless of the type of fiber used in the products. BLDB improved the physical properties of the products by 50% for papers and 85% for paperboards, and the performance of this binder was comparable to a commercial urea formaldehyde resin binder. Thermal pressing, however, did not improve the physical properties of the binder-enhanced paper products. With the addition of the adhesive binder, CEFW and MSWF showed reasonable substitution potential for ONP fiber by providing suitable tensile and bursting strength in the recycled paper products. The critical fiber length, which produced the minimum strength properties for the recycled paper products, was approximately 1020 mm.