Chemical pollution of the environment is widespread with detrimental effects on wildlife. Currently, more than 350 000 different chemicals or mixtures thereof are registered on the global market and the chemical industry is expected to continue its growth. This necessitates an expansion of which chemicals wildlife toxicology studies target. In this thesis, I examine the occurrence and concentrations of 73 contaminants in waterbirds. In Chapter I, I investigate whether classes of common environmental pollutants, viz. bisphenols, benzophenones, phthalate metabolites, benzotriazoles, benzothiazoles, parabens, triclosan, and triclocarban are present in the plasma of breeding female common eiders (Somateria mollissima) from a colony in the Archipelago Sea, Finland. I detected 21 of the 58 contaminants targeted, with bisphenol A and benzophenone-3 being dominant in terms of concentrations and detection frequencies. I found evidence of late-breeding females having higher concentrations of some contaminants compared to early-breeding females. In Chapter II, I continued my investigation of the aforementioned contaminant families in the eider by collecting whole clutches and plasma samples from the mother. I found no evidence of the egg laying order affecting the concentrations of contaminants in the eggs. While 9 contaminants were detected in both eggs and plasma, 8 were detected in only eggs and 4 only in plasma. This, combined with overall higher detection frequencies of many of the contaminants in eggs compared to plasma, suggests that eggs may be a more suitable matrix for monitoring the targeted contaminants in eiders. Finally, in Chapter III, I examined the occurrence of neonicotinoids in plasma samples from female common goldeneyes (Bucephala clangula) breeding across Finland. Interestingly, I did not detect any of the seven targeted neonicotinoids—nor their transformation products—in any of the sampled goldeneyes. While the limits of detection (LOD) may have been too high to detect low levels of neonicotinoids in the females, the LODs were sufficiently low to assess whether neonicotinoid exposure poses a major risk to the goldeneyes. This thesis reveals that waterfowl, as exemplified by the eider, are exposed to a cocktail of contaminants, many of which are severely understudied and more scientific attention should be given to expanding our knowledge of the behaviour and fate of these contaminants in wildlife and in the environment.