Prosecutors in Pierce County charged Ann Rogers and Julio Aguilar-Salazar with three counts of child abandonment for leaving the toddler and two other young children unattended.
The News Tribune says both pleaded not guilty in Pierce County Superior Court and were ordered held in lieu of $150,000 bail.
Charging documents show the 7-year-old girl told a neighbor that she was alone with her two younger brothers.
Police also found the 1-year-old boy in the apartment by himself. The parents arrived home about 15 minutes later, and told police they had left only for a few minutes to fill a prescription for the girl.
The children were placed into protective custody.