One of the primary motivations for JWST is to identify the first luminous sources to form, and determine the ionization history of the universe (see Fig. 1). The emergence of the first sources of light in the universe marks the end of the “Dark Ages” in cosmic history, a period characterized by the absence of discrete sources of light. Understanding these first sources is critical, since they significantly influenced subsequent structures. The current leading models for structure formation predict a hierarchical assembly of galaxies and clusters. The first sources of light acted as seeds for the successive formation of larger objects, and by studying these objects we will learn the processes that formed the nuclei of present day giant galaxies. The first galaxies formed with about a million solar masses of stars radiating strongly in the rest-frame ultraviolet (UV) and visible, which is red shifted into the near IR (NIR). In order to detect these faint sources, JWST requires a large collecting area, excellent image quality at 2 μm, the low backgrounds that come from observing above the atmosphere, and the cryogenic operating temperature of the observatory. By taking very long exposures in the NIR, JWST will be able to see the first stars exploding as supernovae, and the first galaxies as they form. This will require exposures each, in several broadband filters using the near IR camera (NIRCam) instrument. This approach has been especially successful in deep-field observations such as the Hubble deep field,1 the Hubble ultra-deep field,2 and, most recently, the Wide Field Camera 3 (WFC3) deep field,3 as shown in Fig. 2. The tunable filter imager will employ narrow-band imaging surveys to search for emission from these galaxies. Follow-up spectroscopy and images in the mid-IR (MIR) will also teach us more about the objects that are seen in the NIRCam images.