Goblet cell hyperplasia (GCH) and decreased ciliated cells are characteristic of asthma. We examined the effects of IL-13 (2 and 20 ng/mL) on in vitro mucociliary differentiation in pediatric bronchial epithelial cells (PBECs) of normal PBEC [PBEC (N)] and asthmatic PBEC [PBEC (A)] children. Markers of differentiation, real-time PCR for MUC5AC, MUC5AC ELISA, and transepithelial electrical resistance (TEER) were assessed. Stimulation with 20 ng/mL IL-13 in PBEC (N) resulted in GCH [20 ng/mL IL-13: mean, 33.8%(SD, 7.2) versus unstimulated: mean, 18.9%(SD, 5.0); p< 0.0001] and decreased ciliated cell number [20 ng/mL IL-13: mean, 8%(SD, 5.6) versus unstimulated: mean, 22.7%(SD, 7.6); p< 0.01]. PBEC (N) stimulated with 20 ng/mL IL-13 resulted in> 5-fold (SD, 3.2) increase in MUC5AC mRNA expression, p< 0.001, compared with unstimulated PBEC (N). In PBEC (A), GCH was also seen [20 ng/mL IL-13: mean, 44.7%(SD, 16.4) versus unstimulated: mean, 30.4%(SD, 13.9); p< 0.05] with a decreased ciliated cell number [20 ng/mL IL-13: mean, 8.8%(SD, 7.5) versus unstimulated: mean, 16.3%(SD, 4.2); p< 0.001]. We also observed an increase in MUC5AC mRNA expression with 20 ng/mL IL-13 in PBEC (A), p< 0.05. IL-13 drives PBEC (N) toward an asthmatic phenotype and worsens the phenotype in PBEC (A) with reduced ciliated cell numbers and increased goblet cells.