Many states and school systems also set levels of expected achievement, which must be met before promotion. A certain reading, writing, or math level must be attained before a child can be promoted. Children who don't meet the expected levels may receive remediation during summer school before being promoted to the next grade.
It's also helpful to look at social and developmental skills. Does your child get along well with other children who are going to second grade? Are her fine-motor skills as well-developed as those of other children? Your child can be scheduled for a developmental screening, such as the Gesell School Readiness Test to determine her developmental readiness if you're not sure.