There has been limited epidemiologic information concerning preschoolers' behavioral and emotional problems in Eastern societies. This study was therefore aimed to investigate behavioral and emotional problems in a large sample of Taiwanese preschoolers using the Child Behavior Checklist for Ages 1.5-5 (CBCL/1.5-5). The CBCL/1.5-5 was scored by mothers of 645 Taiwanese preschoolers aged 24-71 months. Psychometric features of the scale as well as the raw scores and prevalence rates of behavioral problems of Taiwanese preschoolers were compared with those of American counterparts. Several demographic variables with the Total Problems and syndromes scores were also examined. The CBCL/1.5-5 was found to have good to excellent levels of reliability (internal consistency, test-retest reliability and inter-parent agreement) and an acceptable model fit of seven-syndrome factor structure (root mean square error of approximation=0.055) when used with Taiwanese preschoolers. The prevalence rate of Total Problems, Internalizing syndrome and Externalizing syndrome score in the clinical range was 25.1%, 11.2% and 25.4%, respectively. Cross-cultural comparisons showed that Taiwanese preschoolers had higher scores in six narrow-band syndromes (effect size d=0.17-0.43, all "p"'s less than 0.005) and prevalence rates of four Internalizing-related syndromes and Sleep Problems than American sample (odds ratio=2.4-4.9, all "p"'s less than 0.005). Analyses of behavioral correlates revealed associations of first birth order with higher Internalizing, Externalizing and Total Problems scores (all "p"'s less than 0.05). Furthermore, younger ages (24-47 months) and male gender were associated with higher Externalizing and Total Problems scores (all "p"'s less than 0.05). Our data have provided important epidemiologic information to assist in clinical assessment and management of preschoolers' behavioral and emotional problems in an Eastern society. (Contains 3 tables.)