The rapid development of technological solutions to various environmental and industrial challenges has resulted in the creation of a multitude of novel chemicals, many of which will inevitably find their way into aquatic ecosystems.  To reduce an otherwise endless list of chemical possibilities, we must proactively assess the costs, functionality, and environmental impacts associated with these novel chemicals.  Room-temperature ionic liquids (ILs) are a prominent example of a large class of emerging chemicals being submitted to such proactive ecotoxicology.  These ILs have been shown to have a wide range of toxicities to different aquatic organisms (LC50s of 0.005 to 8000 mg L^-1).  Using standard toxicity tests, mechanistic toxicity studies, microcosm and mesocosm tests, and mathematical modeling, we are now generating a clearer picture as to which classes of ILs should be further developed based on toxicity, biodegradability, and model predictions.  Ideally, a similar integrated process should be applied to other emerging chemical classes (e.g., engineered nanomaterials).  By understanding the broader ecological effects of emerging technologies, incorporating that information into predictive models, and conveying the conclusions to those developing, regulating, and using those chemicals, environmental degradation and costly clean-up will be minimized.