A 12-month-old girl is not yet walking, which concerns her parents. She can pull herself up and stand while holding furniture but does not cruise. Her development was previously assessed as normal. Development is assessed across five domains: gross motor, fine motor, language, social, and self-help skills. Milestones for a 12-month-old include walking, pincer grasp, and social skills like joint attention. Screening tests could further assess her development. Developmental delay is defined as skills significantly below what is expected for age.