Presently, ASD is a neurodevelopmental disorder defined by (a) social-communicative (SC) impairments and (b) impairing restrictive/repetitive behaviors or interests (RRB) present early in development. Parents often identify concerns about their children’s development in the first 2 years of life. Concerns are often shared with healthcare providers when children are 14–18 months old, with some concerns being conveyed as early as 11 months (Chawarska, Klin, Paul, & Volkmar, 2007; Coonrod & Stone, 2004). First symptoms often involve language delay accompanied by social communication delays or deficits. For example, infants and toddler with ASD are often less responsive to their name being called; have difficulties with eye contact; demonstrate less social smiling; show poor imitation skills; or lack imitation skills altogether. During children’s early development, caregivers often report concerns that their child may be deaf due to the lack of social response to their name being called. Early symptoms of ASD also include poor pretend play skills and impairments in joint attention, both in its initiation and appropriate response. The social communicative and play difficulties exhibited by many young children with ASD are part of the repertoire of typically developing children by the age of 18 months. The presence of these symptoms also discriminates between young children with ASD and those with language and developmental delays.

Early symptoms of RRB include unusual toy play (e.g., repetitive play with toys; lining up toys), repetitive interests (e.g., watching same videotape or video clip), and repetitive movements (e.g., hand flapping). Approximately one third of those with ASD experience a period of developmental regression, whereby acquired skills are lost. Regression is most often reported in the area of language development and most often during the ages of 20–24 months (Barger, Campbell, & McDonough, 2013). Despite the presence of early parental concerns and symptoms, the average age of diagnosis for ASD diagnosis in the United States is often reported at 4–5 years of age (e.g., Centers for Disease Control [CDC], 2012). Wiggins, Baio, and Rice (2006) further documented that the average time delay between initial evaluation for developmental concerns and diagnosis of ASD was 13 months. Given these findings, it is important that research and clinical practice continue to focus on reducing the time between initial parental concerns, age of initial evaluation for ASD, and age of diagnosis. By screening for ASD in young children, clinicians have the opportunity to promote earlier evaluation, diagnosis, and access to specialized interventions, which have been shown to improve social, emotional, cognitive, and behavioral functioning in young children with ASD (Dawson et al., 2010; Eaves & Ho, 2004).

Due to the importance of early assessment and targeted interventions for young children with ASD, the field has developed and validated, with some success, screening measures designed to identify autism-specific symptoms in young children. By utilizing screening tools with young children, clinicians are better able to identify children at risk for developmental delays and ASD in order to refer them for more comprehensive evaluations (Meisels, 1985). The current section reviews Level 1 screeners, which are designed to identify children at risk for developmental disorders from unselected, generally low-risk populations, as well as Level 2 screeners, which are used to differentiate children at risk for autism versus those at risk for other developmental disorders.

Screening measures differ in purpose and usability across settings (Zwaigenbaum & Stone, 2006). Specifically, Level 1 screeners tend to be used commonly in pediatric or primary healthcare settings at well-child visits, thus suggesting that these screeners should be quick and easy to administer and score given the limited time clinicians can typically spend with each child. On the other hand, Level 2 screeners are used more frequently in community settings that serve children with a range of disabilities such as early intervention programs or diagnostic centers, which tend to have more time to conduct more interactive, time-consuming evaluations. Despite the differences in the types of screeners, researchers have suggested that multilevel models of screening and a combination of screening tools may be more effective than a single screener in some cases (Miller et al., 2011; Roux et al., 2012). For example, a risk-prevention model, in which Level 2 interactive screeners are used to assess children identified as at risk for autism during Level 1 screening, is designed to increase children’s access to earlier, specialized interventions (Ibañez, Stone, & Coonrod, 2014).