Lakes and lake deposits present two fundamental paradoxes: (1) Modern lakes are vastly complicated, but the rock records of lakes are relatively simple; extensive observations reveal three distinct facies associations of common and widespread occurrence. These are referred to here as fluvial-lacustrine, fluctuating profundal, and evaporative facies associations. (2) Most explanations of modern and ancient lakes attribute their nature to climate, but neither modern lake parameters (lake size, depth, and salinity) nor the character of ancient-lake strata (thickness, extent, lithology) correlate with measured or inferred climatic humidity. We propose that it is the relative balance of rates of potential accommodation (mostly tectonic) with sediment + water fill (mostly a function of climate) that controls lake occurrence, distribution, and character. Lake basins may be termed overfilled, balanced fill, or underfilled, depending on the balance between these rates. We conclude that climate and tectonics exert coequal influence on lake deposits at both mesoscales (1 m to hundreds of meters) and macroscales (hundreds to thousands of meters).