On Tuesday, New Haven Public Schools announced one of its most tangible signs of improvement since its School Change initiative began about three years ago.

The high school graduation rate in the Elm City’s school district increased six percentage points to 70.5 percent in 2012 while the dropout rate decreased by 4.2 percentage points to 21 percent. This is the most substantial rise in graduation rates in New Haven Public Schools since the city’s School Change initiative — which seeks to promote a college-going culture— was launched in 2009. These numbers bring the district closer to two of the initiative’s goals: to cut the dropout rate in half and prepare every student for college.

“The increase in the graduation rate is a testament to the hard work and collaboration of the many partners who work inside and outside of the classroom to keep our students on the difficult four-year path through high school and into college,” said Assistant Superintendent Garth Harries at a Tuesday press conference announcing the improvement. “It is also a testament to the hard work and perseverance of New Haven students, who along with their parents, families and communities play a critical role in the success of School Change.”

When the School Change initiative began in 2009, the district’s graduation rate was 58.1 percent and the dropout rate was at a dismal 31.7 percent. The school change initiative sought to improve these rates through various programs including a teacher evaluation system, the New Haven Promise scholarship, a school tiering system, new extracurricular activities and community outreach events.

As the School Change initiative began to take hold in New Haven Public Schools, the graduation rate rose and the dropout rate fell. In 2010, the graduation rate increased to 62.5 percent and the dropout rate fell to 27.1 percent. In 2011, the graduation rate again inched up to 64.3 percent and the dropout rate fell to 25.2 percent. Now, in the latest and largest jump, the graduation rate is more than 12 percentage points higher than when the initiative began in 2009 and the dropout rate has decreased by approximately 10 percentage points.

“For the fourth year in a row, we have seen New Haven Public School’s graduation rate rise,” Mayor John DeStefano Jr. said at the press conference. “What we are seeing is not an anomaly; what we are seeing are the early results of our nationally acclaimed school change efforts.”

While officials point to these changes as a sign that School Change is on the right track, they have not yet secured the completion of the initiative’s goals. Although the dropout rate has significantly decreased, it has not yet been cut in half. In addition, it is also unclear what percentage of these graduates attends college after graduation, another indicator used by school officials.

Sixty-two percent of New Haven’s 2010 graduating class enrolled in a first year of college and 47 percent of the class enrolled in a second year, according to NHPS spokeswoman Abbe Smith, adding that the rate of students attending a second year of college jumped to 85 percent for first-year New Haven Promise scholars. She said she does not yet know the percentage of graduates who are attending college in 2011 or 2012.

Although the majority of schools did increase their graduation rates, three schools saw a decrease in graduation rates, and one school’s graduation rate remained the same. The school with the largest drop in graduation rates, High School in the Community, is in its first year as a designated “turnaround school,” placing it under the management of the New Haven Federation of Teachers.

The graduation rates are preliminary calculations based on information from the State Department of Education.