The 2013-14 TV season showed no progress in the hiring of female and minority writers, according to the Writers Guild of America, West.
In fact, women and minority groups have recently lost ground compared with their white counterparts, the trade group said.
In a new report, the guild said women writers' share of TV staff jobs was 29% in the most recent season, down from 30.5% in the previous season. Meanwhile, minorities accounted for 13.7% of employment, compared with 15.6% during the 2011-12 season.
The WGA report, released Tuesday, covered about 3,000 writers working on about 300 shows on 36 networks. The declines in the most recent season follow slow gains over the last decade.
"While the general pattern consists of an upward trajectory in diverse sector employment, the rate of progress has failed to keep pace with the rapid diversification of the nation's population," UCLA sociology professor Darnell Hunt, the report's author, said in a statement.
"This is significant not only in terms of employment opportunity but also in terms of industry bottom-line considerations," he added.
Among its other findings, the WGA also pointed to a decline in minorities among executive producers in the TV business, accounting for just 5.5% of positions, compared with 7.8% for the previous season.