A year after the city reduced the influence of test scores on grade promotion and summer school decisions, the number of students headed to summer classes has fallen to its lowest level in six years and the share of students held back a grade has declined by half.

Those numbers, released by the city Wednesday, are among the first signs of the effect of policy changes that barred the use of test scores as a major factor in promotion decisions in response to a 2014 state law. The changes gave principals more discretion when choosing which students should attend summer school and deciding whether they are ready to move on to the next grade.

The changes came after a decade-long push by the Bloomberg administration to curb “social promotion” by not allowing students who scored poorly on state tests to go on to the next grade. That connection became a focus of parents concerned about testing anxiety, prompting legislation and then city policy changes.

Officials said last year that they did not anticipate that the shift would mean fewer students being held back or summer-school numbers dropping, emphasizing that a more holistic approach would lead to more accurate decisions.

But the new figures suggest that the changes have had some immediate impact: The city recommended that about 19,400 third- through eighth grade students take summer classes this year, or 6.2 percent of eligible students, down from 7.4 percent the year before and 10 percent in 2013.

Meanwhile, just 1.2 percent of eligible students were held back at the end of last summer, compared to 2.5 percent of students in 2013 and 3.4 percent of students in 2010.

On Wednesday — the first day of summer school for city students — officials said that principals, superintendents, and teachers were now paying closer attention to student work throughout the year to make decisions about summer school, and that the work portfolios gave more students the chance to show their growth in reading and math.

“We have high expectations for all our students, and our promotion policy reflects our commitment to high standards across multiple measures,” Chancellor Carmen Fariña said in a statement. Officials also said attendance at summer school improved last year, jumping from 77 percent in 2013 to 81 percent in 2014.

The implications of the latest enrollment figures are less clear. Officials noted that more students were recommended for summer school in 2013 because it was unclear how students would perform on new, more difficult state tests. And in many years when the city sent more students to summer school, scores released months later showed that thousands had done well enough to have not required the extra time. Advocates have also raised questions about the efficacy of summer school, pointing to other enrichment programs like Summer Quest, which mixes academics and camp activities, as better options.

Pamela Wheaton of Insideschools, the online guide to city schools, says it’s difficult draw conclusions from the data about whether the right students are getting what they need.

“Do these kids need a program? Yeah,” she said. “But I’m more concerned about what help they’re actually getting once they get to the next grade, because clearly they’re struggling.”