We present Atmospheric Imaging Assembly observations of a structure we interpret as a current sheet associated with an X4.9 flare and coronal mass ejection that occurred on 2014February25 in NOAA Active Region 11990. We characterize the properties of the current sheet, finding that the sheet remains on the order of a few thousand kilometers thick for much of the duration of the event and that its temperature generally ranged between 8 and 10 MK. We also note the presence of other phenomena believed to be associated with magnetic reconnection in current sheets, including supra-arcade downflows and shrinking loops. We estimate that the rate of reconnection during the event was M A ≈0.004-0.007, a value consistent with model predictions. We conclude with a discussion of the implications of this event for reconnection-based eruption models.