Proinflammatory host responses contribute to disease incidence and severity in periparturient dairy cows. Classical phenotype, proinflammatory macrophages were recently described in adipose tissue of periparturient dairy cows undergoing lipolysis. Some nonesterified fatty acids (NEFA) activate macrophage proinflammatory pathways in studies of human disease. However, the impact of NEFA on bovine macrophage phenotype is unclear. The objectives were to model macrophage phenotypes in vitro and assess the effect of periparturient NEFA on macrophage phenotype. Peripheral monocytes isolated by Ficoll gradient and magnetic sorting were cultured with interferon-γ or interleukins 4 and 13 to induce classical or alternative macrophage phenotypes. Macrophage mRNA was quantified using qPCR. Surface protein expression was measured by flow cytometry (n = 8, P < 0.05). After 48 h in vitro, CD172a⁺ was 95.2% ± 0.4% and monocytes became undifferentiated macrophages with increased CD68. Classical phenotype macrophages showed increased CCL2, IL6, TNF, and CD16 expression relative to alternative and undifferentiated macrophages. Alternative phenotype macrophages showed decreased IL6 expression relative to classical and undifferentiated macrophages. Classical macrophages did not change phenotype with lipopolysaccharide stimulation, whereas alternative macrophages showed decreased expression of IL6 and TNF relative to classical and undifferentiated macrophages. A periparturient-like, NEFA mixture increased IL6 and TNF expression in undifferentiated macrophages to levels seen with lipopolysaccharide stimulation. These results demonstrate induction of the classical, proinflammatory macrophage phenotype with exposure to NEFA and suggest that adipose tissue macrophages of periparturient cows are likely polarized to classical phenotype by local NEFA released during lipolysis. Future studies will assess specific fatty acids and transport molecules, and explore the potential impact of classical macrophages on lipolysis in adipose tissue.