#1 Best Private High Schools in New Castle County, DE
St. Andrew's School
Episcopal school · Grades 9–12
One of the 3 largest Christian schools in Delaware
Middletown, DE
A+Overall grade320 students6 students per teacher
2026 lists
Best Private High Schools in New Castle County, DE
Private high schools in New Castle County, DE with the highest overall grades. Top 8 of 8 schools.
#2 Best Private High Schools in New Castle County, DE
The Tatnall School
Independent school · Grades Pre-K–12
One of the 3 largest independent schools in Delaware
Wilmington, DE
A+Overall grade457 students6 students per teacher
#3 Best Private High Schools in New Castle County, DE
Padua Academy
Diocesan school · Grades 9–12
100% of graduates go to four-year colleges
Wilmington, DE
A+Overall gradeAll girls424 students11 students per teacher
#4 Best Private High Schools in New Castle County, DE
Centerville Layton School
Independent school · Grades K–12
Smaller classes than 91% of independent schools nationwide
Wilmington, DE
AOverall grade88 students3 students per teacher
#5 Best Private High Schools in New Castle County, DE
Red Lion Christian Academy
Christian school (nondenominational) · Grades K–12
The largest of 25 Christian schools in Delaware
Bear, DE
AOverall grade695 students10 students per teacher
#6 Best Private High Schools in New Castle County, DE
Aquinas Academy
Independent Catholic school · Grades K–12
The only Catholic school in Bear
Bear, DE
B+Overall grade75 students9 students per teacher
#7 Best Private High Schools in New Castle County, DE
St. Mark's High School
Diocesan school · Grades 9–12
The largest of 15 Catholic schools in Delaware
Wilmington, DE
BOverall grade829 students17 students per teacher
#8 Best Private High Schools in New Castle County, DE
St. Elizabeth School
Diocesan school · Grades Pre-K–12
One of the most diverse private schools in Delaware
Wilmington, DE
BOverall grade364 students12 students per teacher
Grades compare each school's official facts, such as class size, how long it has served families and where graduates go, with similar schools. They're a starting point: visit, ask questions and trust what you see.