The Council on American-Islamic Relations' (Cair) study - the only annual investigation of its kind - outlined 1522 incidents and experiences of anti-Muslim violence, discrimination or harassment in 2004.
The figure, according to Cair's Unequal Protection report published on Thursday, is 50% higher than an assessment made in 2003.
The rights group said factors contributing to the sharp increase in reported incidents included the lingering impact of post-9/11 fears, increased awareness of civil rights issues in the Muslim community and a general increase in anti-Muslim rhetoric.
Other factors for growth in the number of incidents may also include an increase in local Cair chapters reporting cases and alleged abuses associated with the implementation of national security policies.
Ten states accounted for almost 79% of all incidents reported to Cair in 2004, with the majority of attacks reported in California, followed by New York, Arizona, Virginia, Texas, Florida, Ohio, Maryland, New Jersey and Illinois.
By far the greatest increase over last year, in both real and proportional terms, occurred in the areas of unreasonable arrests, detentions, searches/seizures, and interrogations.
In 2003, complaints concerning law enforcement agencies accounted for only 7% of all reported incidents. In 2004, however, these reports rose to almost 26% of all cases.
"These disturbing figures come as no surprise given growing Islamophobic sentiments and a general misperception of Islam and Muslims"
Arsalan Iftikhar, Cair legal director and report's author
But not all the news was bad. There were drops in certain categories from the previous year's report.
For example, workplace discrimination complaints constituted nearly 23% of complaints in 2003, but dropped to just under 18% of total complaints in 2004.
Complaints involving governmental agencies decreased from 29% in 2003 to 19% in 2004.
Cair Legal Director Arsalan Iftikhar, also the report's author, said the findings "come as no surprise given growing Islamophobic sentiments and a general misperception of Islam and Muslims".
Iftikhar said the phenomenon of Islamophobia would be addressed at a Cair conference, called Islamophobia and Anti-Americanism: Causes and Remedies, to be held on Saturday in Washington DC.
Cair Executive Director Nihad Awad added that the rights watchdog called on "President Bush ... to once again speak out against Islamophobic attitudes".
Awad also called on Congress to hold hearings on the findings of Cair's report.
Cair began documenting anti-Muslim incidents following the 1995 attack on the Murrah Federal Building in Oklahoma City. The council is America's largest Islamic civil liberties group, with 31 regional offices and chapters nationwide and in Canada.