The Mental Development Scales: Birth to Three Years are instruments designed to assess developmental levels of young children within a setting familiar to the child. They (1) provide a greater understanding of child behavior and development, (2) serve as a basis for planning an individualized curriculum for each child, and (3) furnish the means for comparing a child with herself or himself over time. They were prepared for use by professionals, including teachers in group settings, day care directors, and professional home visitors. The instrument contains six scales: (1) spontaneous drawing; (2) block play; (3) object exploration; (4) social responsiveness and discovery of selfhood; (5) communication; and (6) play. Each scale is divided into five developmental levels with each scale yielding a separate score. (Author/PN)