The early life history of the federally endangered tidewater goby (Eucyclogobius newberryi) and its sister species the arrow goby (Clevelandia ios) has been poorly documented to date. Both are endemic to estuarine habitats throughout the California coast, however, habitat use differs between these two species. The arrow goby is commonly found in fully marine tidal bays and mudflats. The tidewater goby, however, prefers lagoons with some degree of seasonal isolation from the sea. Here, we used otoliths to examine the larval duration, size at settlement, and growth rates of newly settled gobies collected from 18 estuaries in California. The tidewater goby had a larval duration that was ~2 days shorter than the arrow goby (23.95 vs. 26.11 days, respectively), but a larger size at settlement based on back-calculated size (12.38 vs. 10.00 mm SL) due to a faster larval growth rate (2.86 vs. 2.60 μm/day<sup>-1</sup>). There are several reasons that could explain these differences in larval traits, such as differences in temperature or food resources between the two estuary types, or the faster, annual life cycle of the tidewater goby relative to the arrow goby.