The federally endangered Devils Hole pupfish, Cyprinodon diabolis, is endemic to Devils Hole, a limestone cavern adjacent to Ash Meadows National Wildlife Refuge in Nye County, Nevada. Sampling of the Devils Hole pupfish must be non-obtrusive, thereby limiting researchers to visual observation methods. This thesis assesses current monitoring efforts of Devils Hole pupfish with the goal of improving trend detection. In addition, a population model is constructed from monthly length-frequency distributions with the dual goal of increasing understanding of Devils Hole pupfish life history characteristics and identifying vulnerable Devils Hole pupfish life history stages. This thesis is composed of three chapters. Specifically, suspected sources of error in SCUBA surveys of adult Devils Hole pupfish were evaluated in the first chapter. In the second chapter, statistical power was used to assess sampling effort allocation (e.g., the number of samples, subsamples, and sub-subsamples) for surveys of larval Devils Hole pupfish. Patterns of Devils Hole pupfish survival, growth, and recruitment were evaluated after constructing a simulation model from length-frequency distributions in the third chapter. The ability to detect trends in population abundance, together with a greater understanding of Devils Hole pupfish population dynamics, will help Devils Hole pupfish conservation by allowing managers develop testable hypotheses and evaluate management actions.