In the wake of a partisan uproar last year, the 2015 guidelines for the Advanced Placement United States history curriculum released Thursday feature a more-balanced look at the country, academics say. The guidelines go into effect immediately.

The AP program, which allows high school students to take college-level courses for credit, is administered by The College Board, a private nonprofit corporation. Political conservatives argued that the 2014 guidelines for US history had an anti-American slant that highlighted wrongdoing and downplayed the achievements of the American people.

The most visible clash came last fall in Colorado's Jefferson County, where the school board proposed to review the course framework in order to ensure that it gave a sufficiently positive view of American achievements. Thousands of students and teachers walked out of classrooms and lined the streets in protest.

The protests in the Rocky Mountain State weren’t an isolated occurrence, with pundits, lawmakers, and even the Republican National Committee weighing in.

In Texas, lawmakers threatened to veto AP US history courses, and Ben Carson, a 2016 Republican presidential hopeful, said that students who completed the class with the new guidelines would be “ready to sign up for ISIS,” a common acronym for the Islamic State.

Liberals might see the new guidelines as The College Board caving in to pressure, but the intent was to move the course away from partisanship, says Jeremy Stern, an independent historian who was consulted for the revision.

He saw the right-wing attacks as “overblown.” In Jefferson County, action by the students and teachers stopped the proposal from going forward, and now the three school board members who supported the measure face a recall vote.

History needs to deal with unpleasant topics as much as high achievements, Mr. Stern says. “You can’t just ignore past injustices because you don’t like them.”

But the 2014 guidelines weren't balanced, he suggests. There were “serious problems” with the old version of the framework, which in some cases didn't put American injustices into a broader framework.

For example, presenting British colonialism without a larger discussion about the abuses of European colonialism in general.

For some teachers, the 2014 guidelines were successful precisely because they did add at least some level of context. For years, teachers have complained that the AP US history course guidelines lacked detail. That made it difficult to know what they should focus on.

While critics of the 2014 framework focused on the exclusion of specific historical figures, Davis Burton, a teacher at Southmoore High School in Oklahoma who has taught AP US history for 13 years, said the 2014 guidelines were a “triple-jump forward.”

“As a teacher, I never felt like the old framework was particularly helpful,” Mr. Burton says. “It might have Ben Franklin in it, but there wouldn't be anything about what Ben Franklin means in the larger context of American history.”

The new 2015 guidelines now reflect more the idea of the unique characteristics of the United States, including the fact that the majority of the country is made up of immigrants, says Jon Butler, an emeritus professor of American Studies at Yale University. Most of the changes he saw were tightening up language and removing elements that might be confusing.

The guidelines are not a set curriculum. They are meant to guide teachers in general subject matter. Stern sees the new guidelines as an improvement.

“This is a major success for an unpolitical look at American history,” Stern says.