The use of Oil Palm Shell (OPS) as coarse aggregate is a cost-effective approach in the production of structural lightweight concrete. The aim of this book is to investigate the time-dependent deflection performance of palm shell aggregate concrete beams for the period of four months sustained loading condition. Both experimental and theoretical studies are carried out on 1.5m long beams to investigate their structural behavior. Factors affecting the short and time-dependent deflections of palm shell aggregate concrete beams are employed in this book. The experimental results are compared with the theoretical results. The theoretical approach can give conservative estimate of the deflection provided the factors affecting the time-dependent performance of palm shell concrete beams are addressed. It is concluded that partially replaced oil palm shell aggregate concrete beam has the potential to be used in the construction of low-cost structures. The paper also highlighted the beams failure modes due to the replacement of palm shell aggregate on the conventional coarse aggregate.