Targeting constructs that contribute to positive and negative affect may lead to clinically significant reductions in symptoms of principal and co-occurring psychopathology. Anxiety sensitivity, the fear of negative evaluation, and illness/injury sensitivity have been described as three fundamental fears that underlie anxiety-related disorders. Despite the contemporary relevance of the fundamental fears, positive affect, and negative affect as treatment targets, research into how these constructs relate to each other remains scant. Community participants (n = 287) completed measures of affect and the fundamental fears. Canonical correlations, regression analyses, and moderator analyses revealed strong associations between negative affect and each of anxiety sensitivity, the fear of negative evaluation, and illness/injury sensitivity and a weaker but significant inverse relationship with positive affect. The fundamental fears shared a substantive amount of variance (42 %) with positive and negative affect, and this overlap may warrant attention from researchers and clinicians focusing on specific or transdiagnostic features of anxiety.