Aspergillus fumigatus is an opportunistic human pathogen associated with human disease in individuals of both the hypo- and hyper-immune states. Infection within the lung begins with the inhalation of dormant spores that can either cause hyper-immune responses such as Allergic Bronchopulmonary Aspergillosis (ABPA), a severe form of asthma, or invasive growth (Invasive Aspergillosis, IA) in the hypo-immune due to insufficient host recognition, neutralization, and/or clearance of spores. The signals governing germination or invasive growth which are paramount to the development of these diseases are poorly understood. Oxylipins are cross-kingdom signaling molecules with documented roles in mammalian immune responses, plant defense, and fungal development. Oxylipins produced by human cyclooxygenases and lipoxygenases are well-characterized and modulate many immunological responses associated with allergy and asthma. While A. fumigatus encodes three cyclooxygenase and two lipoxygenase homologs, their role in fungal development and modulation of host immune responses has not been thoroughly investigated. This thesis finds that disruption of an A. fumigatus lipoxygenase results in a significant germination defect in the presence of the polyunsaturated fatty acid, arachidonic acid (AA), likely due to the lack of of an AA-derived oxylipin signal that promotes spore germination in the presence of AA. Overexpression of this lipoxygenase (OE::loxB) accelerates germination, but yields a more allergenic strain as extracts from the OE::loxB strain cause an increase in airway hyperresponsiveness, macrophage and eosinophil recruitment, and serum IgE levels in a murine model of asthma. Investigation of an A. fumigatus cyclooxygenase homolog (PpoA) reveals its cognate oxylipin products play a critical role in asexual spore development, production of immuno-modulatory metabolites, and hyphal branching. Collectively, the following chapters provide novel insight into 1.) host recognition of A. fumigatus spores and 2.) the pivotal role of two fungal oxygenases. Specifically germination, secondary metabolite production, and hyphal branching are examined which are lucrative drug targets for the control of human fungal disease.