In the first part of the dissertation a new manufacturing method, Bladder Assisted Composite Manufacturing (BACM), to fabricate geometrically complex, hollow polymeric composite parts is presented. The BACM process utilizes a bladder to provide the necessary consolidation pressure and cures the part by circulating heated air inside the bladder. The feasibility of this manufacturing process is demonstrated by fabricating laminated composite cylinders using multiple numbers of plies, cure pressures, and mold configurations. Using the described process, a number of 2-, 4-, and 6-ply composite cylinders made of either Newport 321/7781 glass/epoxy or TenCate® EX-1522/plain weave carbon/epoxy prepregs were prepared as test samples. Cylinders were cured at the manufactures recommended cure temperatures and hold times using bladder pressures ranging from 207 kPa (30 psi) to 621 kPa (90 psi). The fiber volume fraction, void content, mechanical properties, and energy consumed during the curing of the composite cylinders, are investigated and compared to traditional manufacturing techniques. The fiber volume fraction and the void content of the cylinders were determined from resin burn-off experiments and density measurements. The mechanical responses of these cylinders were characterized by diametrically compressing sample rings and loading ring segments in three-point bending configuration. The fiber volume fractions of the cylinders were observed to be dependent on both the bladder pressure and mold configuration used, reaching a maximum of 66% for the cylinders made from the TenCate® material. The elastic moduli and failure strengths of the cylinders were found to increase with fiber volume fraction regardless of mold configuration used, reaching maximums of 61.5 GPa and 1272 MPa respectively for the TenCate® material. The void content was found to be dependent on mold configuration and was minimized to 0.2%. Compared to conventional bladder manufacturing methods, the BACM process reduced the energy required to cure the cylinders by more than 50%. The second part of the dissertation involves the development of new void formation and mechanical effect models. These models were developed by manufacturing eight-ply laminates from TenCate® BT-250/7781 prepreg at cure pressures ranging from 69 kPa (10 psi) to 483 kPa (70 psi) by hot-press. For each cure pressure, a laminate was fabricated from prepreg, which were direct from the bag and conditioned at 25%, and 99% relative humidity for 24hrs at 25°C. The manufactured laminates’ void contents were found to vary from 1.6-5.0% depending on humidity environment and the applied cure pressure and were observed to approach an asymptotic value of approximately 1.6% as cure pressure was increased. The available predictive model for process-induced voids was not found to be capable of accounting for this. Therefore, the model was modified by the addition of a pressure reduction and asymptotic void content terms. The integration of these two terms resulted in a void formation model, which shows excellent agreement with experimental data. The experimental evidence indicates that the presence of voids only affects tensile strength significantly and the effect of voids on strength increases with fiber volume content. For example, the tensile strength of the laminates were found to decrease by 2.7%-23% for every 1% void content as the fiber volume content was increased from 45%-57%. This effect is explained by the voids becoming increasingly in contact with and elongated along the fibers as fiber volume content is increased. These findings resulted in a void effect model capable of accurately predicting the influence of voids as fiber volume content is varied.