This investigation studied the aerodynamic performance of an NLF(1)-0414F natural laminar flow airfoil with flap deflection and ice accretions. Four models, each incorporating a different ice protection system, were tested in the NASA Lewis Icing Research Tunnel to acquire inter-cycle ice shapes for each ice protection system and a failure mode ice shape. Two-dimensional simulations of the failure-mode and inter-cycle ice accretions were created using stereo lithography and tested in the University of Illinois wind tunnel to acquire C_l, C_d, C_m, and C_h data. Three spanwise cross-sections of the failure-mode ice shape as well as a LEWICE prediction were tested to evaluate the effect of variations in the ice shape along the span of the model. Significant differences were found in the aerodynamic performance. Boundary-layer measurements were made through the use of a boundary-layer mouse and the boundary-layer thickness correlated well to the drag values. Lower surface ice roughness aft of the main accretion was modeled and found to have little measurable aerodynamic effect. All ice accretions tested degraded the aerodynamic performance, but the intercycle ice simulations saw larger C_l,max degradation, compared to the accompanying drag rise, than did the failure-mode ice shapes.