The goal of this work was to enhance membrane performance by achieving high, well-dispersed loadings of a metal-organic framework: MIL-101. Thin film nanocomposite (TFN) membranes fabricated using n-hexane as an organic phase demonstrated significant aggregation, which reduced selectivities and stochastically increased permeances. Solution-phase measurements confirmed aggregation of MIL-101 in n-hexane and showed that nitrobenzene created well-dispersed suspensions at concentrations as high as ~0.14% (w/v). Nitrobenzene was used for the first time to make TFN membranes. Membrane performance, composition and morphology were correlated to the presence of aggregates in solvents. When aggregates were present, non-selective or semi-selective defects were found. Well-dispersed MIL-101 prevented defect formation.TFN membranes were fabricated using nitrobenzene under two reaction conditions, one leading to smoother membranes and the other leading to rougher membranes. When increasing the MIL-101 loading in the organic phase, the smoother membranes showed no changes in permeance or rejection, while the rougher membranes showed an up to 3.6-fold increase in permeance with negligible changes in rejection (neutral dye, 314 g·mol−1). These data suggest that changing the interfacial polymerization conditions to produce rougher membranes enables filler materials to have a more significant impact on membrane performance.