This is a single site, open-label, four-week feasibility study of long-duration beaded methylphenidate (B-MPH), also known as Ritalin LA™. B-MPH is a FDA-approved medication for children 6 years and older with attention-deficit/hyperactivity disorder (ADHD), but there are no studies of its use in preschoolers. This study will evaluate the safety and effectiveness of B-MPH for ADHD treatment in 4-to-5-year old children.

Total study duration is approximately 5 weeks. It includes a screening evaluation and 4 weeks of B-MPH treatment with doses ranging from 10 to 30 mg (based on the individual tolerability and efficacy). The study doctor will conduct parent-training sessions during the treatment visits.

Inclusion Criteria:

1. Parent/legal guardian provided informed consent; child provided verbal assent
2. Parent and child must be English-speaking
3. Child must be in good physical health
4. Child must be stimulant-naïve, OR not on ADHD medication, OR taking ADHD medication but not finding it helpful
5. Child must have an IQ of at least 70
6. Child must be in an educational setting (e.g., pre-school, kindergarten, elementary school program) at least two half days weekly

Exclusion Criteria:

1. Child with adjustment disorder, autism, psychosis, bipolar disorder, significant suicidality, or any other psychiatric disorder
2. Child with current or history of physical, sexual, or emotional abuse
3. Child with history of intolerance to stimulant medications
4. Child who did not respond to adequate stimulant medication trials
5. Child taking medications that are excluded in the study
6. Child and parent refusing to comply with study procedures