To develop a continuous measure of child problem behavior in early childhood, we selected items from the Child Behavior Checklist (CBCL; Achenbach & Rescorla, 2001) that describe defiance, opposition, and aggressive behavior. The CBCL asks parents to rate the validity of several statements regarding potential child behaviors on a 3-point Likert scale in which 0 = not true; 1 = somewhat, sometimes true; and 2 = very true, often true. A scale was then computed by averaging the values for problem behavior items at each assessment age. Because the CBCL changes items at age 5, there were only 8 oppositional-defiant and aggression items that were continuously present on the CBCL across ages 2 through 5 were used. Alpha reliabilities for the Problem Behavior scale were acceptable at all four ages (.71 at age 2, .75 at age 3, .78 at age 4, and .80 at age 5).
