Let's see if I can elaborate a bit...
The Knights of Labor began as a secret society of tailors in Philadelphia in 1869. During the 1870's the Knights membership grew slowly but as the level of worker militancy rose towards the end of the decade, encouraged by the great railroad strike of 1877, the Knights membership skyrocketed. A gentleman by the name of Terence V. Powderly, with the title Grand Master Workman, took office in 1879. Under his leadership the Knights flourished. By 1886, membership was estimated to be about 700,000. Powderly got rid of the earlier rules of secrecy and advocated the eight hour work day, abolition of child labor, equal pay for equal work. He also used the political clout of the organization in seeking reforms, most notably the graduated income tax.
Breaking ranks with other trade unions of the day, the Knights unions were vertically organized. This meant that each union included all workers in a given industry, regardless of trade. Some other things that made the Knights different and unusual were their acceptance of workers of all skill levels and both male and female workers were also allowed admission. Blacks were included for admission in 1883 although they were still required to maintain segregated locals. In direct contrast, the Knights also supported the Chinese Exclusion Act of 1882. Union leadership felt that laws like this were needed to protect the American work force from underpaid laborers that were imported by employers. (Sound familiar?)
Although the union leadership believed in boycotts and arbitration - they opposed strikes. They had only marginal control over union membership however a successful strike by the Knights against Jay Gould's railroad system brought in a flood of new members.
The downfall of the Knights began after a subsequent strike against Gould's railroads was badly beaten. Against union leaderships objections, other members of the Knights participated in a general strike that began in Chicago on May, 1 1886. On May 4, a bomb explosion at a workers rally triggered the Haymarket Massacre. as a result a national wave of arrests and repression began. Labor activism of every kind suffered severe setbacks. The Knights were particularly singled out for blame and by 1890 membership had fallen to less than 100,000.
Although erratic leadership and the rise of factions within the unions contributed to the decline in the strength of the Knights, the general repression of labor unions as a whole in the 1880's was also a contributing factor.