The Social Phobia and Anxiety Inventory for Children-11 (SPAIC-11) and Social Phobia and Anxiety Inventory for Children's Parents-11 (SPAICP-11) were developed as brief versions of the Social Phobia and Anxiety Inventory - Child and Parent Versions via item response theory (IRT) using child and parent reports of social anxiety. A sample of 496 children was analyzed using IRT analyses, revealing 11 items that exhibit measurement equivalence across parent and child reports. Descriptive and psychometric data are provided for the child, parent, and combined total scores. Discriminant validity was demonstrated using logistic regression and receiver operating characteristic curve analyses. The SPAIC-11 and SPAICP-11 are psychometrically sound measures that are able to measure social anxiety invariantly across children and their parents. These brief measures which include combined parent and child perception of the child's social anxiety may provide notable benefits to clinical research.