K/S & K.S. (Kindred Spirits)
The membership cap was 30. In 1992, the membership was down to 16 and members were actively soliciting new contributors. In January 1993, The LOC Connection's editor imposed a 750-word limit probably bolstered the numbers.
From an ad in Media Monitor #34: "K/S & KINDRED SPIRITS, (The APA) - This letter zine is devoted to the Kirk/Spock relationship. Published every two months, members must contribute one out of every three mailings. Cost is postage. SASE for more details."
AboutIn 1992, a member explained the APA to other K/S fans:
As a long-time member of "K/S and K.S. (Kindred Spirits) the APA" I am happy to comply. As the title suggests, our APA is for K/S fans; those who are active in writing, illustrating and publishing zines as well as those who read them. The discussions cover different aspects of K/S, STAR TREK in all its forms, plus a myriad of other topics. One thing leads to another, and this adds up to a rich and varied mix of interesting, insightful talk. Everyone is free to add to the discussion. Members often include short stories or segments of longer ones in progress, in the APA, inviting reactions and suggestions. A new member generally gives a short bio as her intro- zine. She tells about her life outside of fandom and how she became interested in ST and K/S. She may comment on anyone else's apazine or bring up subjects that she'd iike feedback on. It may seea a little overwhelming, at first, to jump in on the ongoing discussions, but by contributing regularly, you soon get addicted to it and can't wait for the next issue. The ground rules allow members to contribute as little as once in three issues, but the secret to getting the most- out of the experience is to contribute often, the only cost is postage and making copies of your trib which can be any length. These go to the CH (Central Mailer) who collates and mails out the issues every two months. 
Membership Info and Stats
The 1988 and 1989 listing in The New Moon Directory said the apa had "room for 3 or 4 new members."
The 1990 listing in NMD said it had 20 members and it was a "long-running apa devoted to K/S and Star Trek. Issues discuss episodes, zines, cons; sometimes contains poetry or prose by members. Introducing or commenting on Trek-related topics the "official format," but personal news and general topics are also discussed."
The 1991, 1992 and 1993 listing in NMD said it had 22 members. The 1995 and 1996 listing said there were 16 members.
From the 1997-98 description in The New Moon Directory : "bimonthly; copy count 14; 13 members; minac 1 pg/3 issues; no maxac; dues = positive postage account; open roster, no limit; no waitlist; spec copies available for postage; back issues available for postage. Long-running apa devoted to K/S and classic Trek. Issues discuss the series, movies, fanzines and cons at an adult level. Members must be over 21! Introducing or contributing thoughts on Trek-related topics for discussion is the official format, but other topics such as ST:TNG, different fandoms or personal news is also permitted."
According to the cover of issue #28, some contributors at the time were T'Purr, Vel, Cora, Alta, Cicatrice, William, Laurie, Susan, Beth, Ruth, Pat, Dorothy, Sydney, Linda, T'Rhys, Judith, Morjana, Sandra, Dawn, Liz, Joanne, and Jatona.
The Move to Online
In 1996, the members of this apa became part of K/S Circle, the first online K/S forum: "I had been a member of the K/S & Kindred Spirits Amateur Press Association (APA), which had been running since the mid-1980s. It was a private correspondence group that put out a print publication every other month or so, which was (snail) mailed only to the members. Around 1995 and 1996, a few APA members acquired accounts and began emailing one another, individually. At some point it occurred to me that it might be fun for all of us to be able to participate in one another’s conversations, as we had in the APA. We kicked around the idea, discussing the pros and cons. The first “pro” was that we wouldn’t have to wait two months to hear back from the others. However, some people were quite leery about what such a group would mean to an individual’s privacy. We decided that the K/S Circle would be a private group, similar to the APA. Any current member could propose (and vouch for) a new person for membership. All members had to agree to the ground rules, which included using our real names and not allowing anyone outside the group access to the group’s postings." 
K/S & K.S. (Kindred Spirits) 4 has a cover by Bright.
K/S & K.S. (Kindred Spirits) 6 was published around 1982.
K/S & K.S. (Kindred Spirits) 9 was published around 1984. It has a cover by Paula J. Mathas.
K/S & K.S. (Kindred Spirits) 20 was published around 1984.
K/S & K.S. (Kindred Spirits) 38 has a cover by Dorothy Loang.
K/S & K.S. (Kindred Spirits) 41 was published in March 1990.
K/S & K.S. (Kindred Spirits) 41 was published around July 1992.