Does life currently exist, or did life once exist, on other worlds in our solar system? The proximity of the rocky planets of our solar system, Venus and Mars, make them obvious targets for the first attempts to answer these questions via direct exploration, with concomitant implications for, and input to, how we think of exoplanets. Given the limited resources we have to explore our neighbors in space, an ecological assessment (based on terrestrial ecosystem principles) might help us target our search and methodology. Studies of extreme life on Earth consistently reveal adaptability. Mars has been the target of many life-related investigations [1, many others]. Venus has not, yet there may be compelling reasons to think about extant life on the second planet [2], and lessons to learn there about searching for life elsewhere in the solar system and beyond. The Venus Life Equation: Venus may have been habitable for billions of years its history and may still be habitable today. Our current state of knowledge of the past climate of Venus suggests that the planet may have had an extended period – perhaps 1-2 billion years – where a water ocean and a land ocean interface could have existed on the surface, in conditions possibly resembling those of Archaean Earth [3]. At present, Venus’ surface is not hospitable to life as we know it, but there is a zone of the Venus middle atmosphere, ~55 km altitude, just above the sulfuric acid cloud layer, where the combination of pressure, temperature, and gas-mix are more Earth-like than anywhere else in the solar system [2, 4]. The question of whether life could have – or could still – exist on the Earth’s closest neighbor is more open today than it’s ever been. Here we approach the question of present-day life on Venus in a manner analogous to the Drake Equation [5], treating the possibility of current Venus life as an exercise in informal probability – seeking qualitatively the likelihood or chance of the answer being nonzero.The working version of the Venus Life Equation is expressed as: L = O * R * A where L is the likelihood (zero to 1) of there being life on Venus in the present-day, O (origination) is the chance life ever began and “broke out” on Venus, R (robustness) is the potential current and historical size of diversity of the Venus biosphere, A (acceptability) is the chance that conditions amenable to live persisted spatially and temporally to the present. The Venus Life Equation is a work-in-progress as a pre-decadal White Paper [6] and its variables are currently being refined. [1] McKay 1997, Springer, Dordrecht, 1997. 263-289. [2] Limaye et al. 2018 Astrobiology, 18(9), 1181-1198. [3] Way et al. 2016 JGR 43(16) 8376-8383. [4] Schulz-Makuch et al. 2004 Astrobiology 4, 11-18. [5] Burchell 2006, Int. J. Astrobio, 5(3) 243-250. [6] Izenberg et al. 2020, https://is.gd/vd4JE7 (location of Latest version of Venus Life Equation White Paper).