The Cambridge Public Schools lack a coherent plan for improving student performance and the district’s central administration is disorganized and uncoordinated, according to a report presented yesterday by a Kennedy School of Government institute.

“When school leaders...are asked what the school system’s strategy for raising student achievement is, they cannot identify a single, unifying strategy,” said the report, which was authored by Lewis H. Spence ’69, past head of the Cambridge Housing Authority and a former deputy chancellor of the New York City Board of Education.

Spence praised recent developments in local schools, which have created new departments to oversee teacher training and analyze student test scores. But he wrote that these offices have “unclear and confusing” mandates and also cited the district’s “incoherent” sets of student achievement goals.

The report, which was funded by the Rappaport Institute for Greater Boston, came at the request of Cambridge Superintendent of Schools Bobbie J. D’Alessandro, who asked the Rappaport Institute about a year ago to commission a study of school administration in Cambridge.

“I think some of it we very much agree with,” D’Alessandro said of the report’s recommendations. “For this coming year, I don’t think we can do the entire package.”

In his report, Spence proposed an ambitious series of reforms focused on improving professional development for teachers. The school district should consolidate its goals for improving student achievement, Spence said. He also said the superintendent needs to appoint a deputy to coordinate the district’s professional development and student achievement offices, and he said the more than 30 administrators who work on developing district-wide curriculum should be reassigned or eliminated.

He also advised untangling relations between the School Committee and school district administrators by hiring “coaches” to advise them on how to improve their working relations.

Spence, who was recently appointed commissioner of the Massachusetts Department of Social Services, the state’s child welfare agency, spent three months interviewing Cambridge school administrators, members of the School Committee and a focus group of teachers before presenting his findings yesterday.

He blamed the large size and disorganization of the school department administration on the Cambridge tradition of giving schools wide latitude to develop their own educational programs, rather than pursuing system-wide initiatives.

“Everything the central office does has to be customized and renegotiated time and again” to fit each individual school, he said.

Though he faulted the district’s overlapping and uncoordinated programs, Spence sounded optimistic notes about recent developments. The drafting of a system-wide District Improvement Plan has resulted in “a greater focus on teaching and learning,” he wrote.

The Rappaport Institute, now in its second year, holds seminars for local elected officials and is planning a series of books on Boston-area public policy issues such as transportation and housing.

Spence’s report, titled “Better Management for Better Schools,” was the first critical evaluation of local government commissioned by the Rappaport Institute, said Executive Director Charles C. Euchner.

—Staff writer Andrew S. Holbrook can be reached at holbr@fas.harvard.edu.