Pakistan, Afghanistan, and Nigeria remain the only countries where endemic wild poliovirus type 1 (WPV1) transmission continues. This report describes the activities, challenges, and progress toward polio eradication in Pakistan during January 2015-September 2016 and updates previous reports (1,2). In 2015, a total of 54 WPV1 cases were reported in Pakistan, an 82% decrease from 2014. In 2016, 15 WPV1 cases had been reported as of November 1, representing a 61% decrease compared with the 38 cases reported during the same period in 2015 (Figure 1). Among the 15 WPV1 cases reported in 2016, children aged <36 months accounted for 13 cases; four of those children had received only a single dose of oral poliovirus vaccine (OPV). Seven of the 15 WPV1 cases occurred in the province of Khyber Pakhtunkhwa (KP), five in Sindh, two in the Federally Administered Tribal Areas (FATA), and one in Balochistan (3). During January-September 2016, WPV1 was detected in 9% (36 of 384) of environmental samples collected, compared with 19% (69 of 354) of samples collected during the same period in 2015. Rigorous implementation of the 2015-2016 National Emergency Action Plan (NEAP) (4), coordinated by the National Emergency Operations Center (EOC), has resulted in a substantial decrease in overall WPV1 circulation compared with the previous year. However, detection of WPV1 cases in high-risk areas and the detection of WPV1 in environmental samples from geographic areas where no polio cases are identified highlight the need to continue to improve the quality of supplemental immunization activities (SIAs),* immunization campaigns focused on vaccinating children with OPV outside of routine immunization services, and surveillance for acute flaccid paralysis (AFP). Continuation and refinement of successful program strategies, as outlined in the new 2016-2017 NEAP (5), with particular focus on identifying children missed by vaccination, community-based vaccination, and rapid response to virus identification are needed to stop WPV transmission.