The contemporary movement for lesbian/gay liberation was born out of the ferment of the New Left. Its leftist roots were openly acknowledged. Theorists such as Dennis Altman, John D’Emilio, David Fernbach and Mario Mieli. All identified with one socialist or communist current or another. All acknowledged their debt to Marxism as well as feminism and psychoanalysis.
Times have changed. Lesbian/gay movements have grown and won some significant victories in the past quarter-century, while the socialist left has shrunk to a shadow of what it was. Unsurprisingly, nowadays lesbian/gay spokespeople and theorists are less likely to identify with the anti-capitalist left than they used to be.
Back to Basics
Lauritsen’s and Thorstad’s roots go back to the U.S. Socialist Workers Party. They broke with that group in the mid-1970s when the word came down from its leadership that lesbian/gay oppression was only a "secondary" contradiction for which members’ energies often could not be spared. But the 1995 edition of "The Early Homosexual Rights Movement" contains few major changes. Like the 1974 version, it treats the pioneers of lesbian/gay emancipation with only mildly critical sympathy and stresses the bright side of their alliance with leftist parties.
This makes the book useful reading for anyone who wants to begin by grasping a few basic facts. For example: in the years before the First World War, the German Social Democratic Party was in the forefront of the fight to repeal that country’s anti-gay Paragraph 175. Eduard Bernstein defended Oscar Wilde (himself an iconoclastic socialist) in the pages of the SPD’s theoretical journal, "Die Neue Zeit."
The Bolsheviks repealed anti-gay laws when they took power in Russia, and supported the pro-gay World League for Sexual Reform throughout the 1920s. The German Social Democratic and Communist parties were the gay movement’s best allies in the 1920s. These basic facts are worth reiterating, if only because some recent scholarship has managed to overlook them.
There is another side to the story. Trained in the Trotskyist tradition, Lauritsen and Thorstad have a keen eye for the (many) failings of social democrats and Stalinists. The German Social Democrats succumbed to the temptation to gay-bait when samesex scandals among the German empire’s aristocratic elite emerged; Social Democrats and Communists succumbed again when Nazi SA head Ernst Roehm was available as a homosexual target.
Stalin re-criminalised homosexuality in the USSR in 1934. Communists in many countries obediently turned their back on their earlier stands and began to identify gays with bourgeois decadence and even fascism. By the time lesbian/gay liberation went though its resurgence in the 1960s and 1970s, an uphill battle had to be fought against anti-gay prejudices inside much of the left.
Lauritsen’s and Thorstad’s focus on Germany helps them avoid noting that the left in other countries, like the United States and the Netherlands, fell short even of the German left’s mixed record. Beginning their account late in the nineteenth century saves them from mentioning Marx’s and Engels’ homophobia, which surfaced not only in private letters but in published writings. Ending in the 1930s saves them from discussing the shortcomings of later, even anti-Stalinist Marxists.
Ambivalent left tradition
"Gay Men and the Sexual History of the Political Left" has been put together with more scholarly thoroughness. It benefits from two decades of accumulating research, and suffers from no inhibitions about exposing the left’s shortfalls. The result is a set of valuable investigations. The strong development of gay studies in Dutch universities (where two of the three editors are based) is well reflected.
The one contribution that focuses on the Netherlands (by Gert Hekma) is a useful demonstration of just how ambivalent early socialists were about sexuality. The anthology also does well to look at several different left traditions - "utopian" socialism, anarchism and Marxism - in a single volume. For anyone who wants to learn about topics as varied as how Andre Gide squared his homosexuality with sympathy for the USSR, what the early Frankfurt School had to say about gays, or the complementary roles of East Germany’s Lutheran Church and Stasi (secret police) in creating a gay movement there, this book is a good starting place.
Yet most of the authors are hampered by three major flaws in their approach. First, though many of them clearly have leftist sympathies, their methods owe little to the left. They work as empiricist historians; few of them seem to see how Marxism, feminism or any other radical paradigm can help them analyse societies. Second, the book as a whole is marred by a double standard, in which Marxist traditions are more harshly judged than others. Third, few of the authors have learned much from social historians’ discoveries about the lives of ordinary gay men and lesbians, who after all made up past movements and parties.
Public vs. private
In their introduction, the editors say that "socialism is singled out for particular attention here because its project was, and is, to fulfil the emancipatory goal of the Enlightenment: the universal liberation of humankind from oppressive ideologies and exploitative social structures." (p7) This argument for holding the left to high standards is absolutely right.
The editors are also right to criticise socialist credulousness about "scientific" biology and medicine, which contradicted the left’s distinctive emphasis on historical and social factors, and to criticise socialist praise of working-class "manliness", which ignored the female half of the working class. But they fail to grapple with the difference between abstract application of principles and a project of liberation carried out by concrete historical agents emerging from really existing capitalism.
Ultimately, when the editors appeal to the classical liberal distinction between public and private realms, they are judging the left by criteria that are alien to the left. "The private sphere has enjoyed far less protection under socialist regimes than under liberal ones," they say.(p16)
They do note in passing that liberals (in the European sense of constitutionalist, secular free-market advocates) were inpractice usually even more anti-gay than leftists. But they fail to explain why. In fact the liberal private-public distinction leaves straight male power in the family unchallenged. Women’s and lesbian/gay liberation require transforming the family in ways that are bound to "interfere" in "private" life.
The authors’ not very profound methodology sometimes limits their predictive ability. For example, in his article on contemporary France, Jan Willem Duyvendak moves beyond his earlier work in describing the difficult "balance between desires and interests" that gay movements need to strike.(370) But lacking a deep analysis of how much those desires and interests are repressed in France today, he predicts continuing demobilisation of French gays - who in fact began mobilising in steadily more impressive numbers before the ink on his article was dry. 
The book’s liberal critique of the left’s sexual politics is limited mainly to Marxists. Saskia Poldervaart’s essay on utopian socialists and Walter Fahnders’ on German anarchists are not just sympathetic, but almost wholly uncritical accounts, citing inspiring passages from their subjects’ works without paying much attention to the reality of their movements
It is valuable to recover these lost voices of sexual radicalism, to note sex-radical insights in Fourier that Marx dismissed, or anarchist pro-gay positions that were better than those of contemporary Marxists.
Anarchist Hubert Kennedy exposes Marx’s homophobic attacks on gay German Lassallean leader Johann Baptist von Schweitzer, though without shedding much light on the issues between Marxists and Lassalleans that probably concerned Marx more.
Richard Cleminson’s careful, historically informed research on the Spanish anarchist "Revista Blanca" sets a higher standard, however, in an article that shows how anarchist puritanism gave way in the 1930s to greater tolerance.
The articles focusing on Marxists mostly fall short of Cleminson’s achievement. In fact, of the ten contributions that deal mainly with avowed Marxists, only two or three show much knowledge of Marxism. Four deal largely with Stalinist regimes or spies; twenty years after Lauritsen’s and Thorstad’s basic exposition, these articles make little distinction between Stalinist sexual politics and earlier Marxist positions.
Laura Engelstein, writing about Soviet legislation, ends up asking in bewildered ignorance, "Why did homosexuality escape the law between 1917 and 1934? That is the still obscure and intriguing tale."(p173) Harry Oosterhuis, who chronicles anti-gay statements in Social Democratic and Communist anti-fascist propaganda of the 1930s with justified indignation, blames the homophobia on Marxism as such; he either does not know or prefers to forget that earlier socialist positions were more pro-gay.
David Thorstad, who contributes the one article dealing withthe U.S. left, is of course knowledgeable about Marxism. He lays out the reactionary positions of the CP and Maoists at the time of the 1969 Stonewall rebellion, cites the enlightened comments of Panther leader Huey Newton, exposes the limits of the SWP’s position, and contrasts it with somewhat better positions taken by other Trotskyist groups.  He rightly criticises positions that in the best of cases tend to dress up defences of minority rights in radical-sounding verbiage instead of attacking the deeper roots of heterosexism.
Unfortunately Thorstad chooses as his decisive criterion agreement with his and Lauritsen’s demand for repeal of age -of-consent laws. Thorstad and Lauritsen have every right to be bitter: The attacks on them not only by the FBI and Jesse Helms but also from within the lesbian/ gay movement have been appalling.
Sadly, this seems to sour Thorstad’s vision of the movement as a whole. The same sourness disfigures the "Afterword to the Revised Edition" of "The Early Homosexual Rights Movement." "The mainstream gay organisations of the present" are dismissed as "politically correct zombies," and the "radicalism of such groups as Queer Nation" as "bizarre and offensive behaviour." (102) Substantive lesbian/gay radicalism is certainly on the defensive, but the scene is not quite as bleak as Lauritsen and Thorstad paint it. 
Class and Community
Manfred Herzer’s article on "Communists, Social Democrats, and the Homosexual Movement in the Weimar Republic" stands out in "Gay Men and the Sexual History of the Political Left," not only for its sense for historical context but also because it points to new frontiers for investigation.
Herzer shows how other writers wrench quotations from the Social Democratic and Communist press out of context, simply editing out reaffirmations of opposition to anti-gay laws that are inconvenient for anti-Marxist arguments.
German gay leaders, he shows, whatever their personal politics, acknowledged the crucial support their movements received from the left. But he goes further and deeper, pointing out that gay leaders treated Nazis like Roehm with kid gloves and failed to mobilise their own members against fascism because a high proportion of their membership was right-wing. Herzer has no explanation for the disproportionate right-wing sympathies of the gay movement’s rank and file: this would require a far-reaching "social" history and analysis of the pre-war community.
Only in the last few years have gay historians begun to explore in depth the historical interaction of sexuality andclass. George Chauncey’s "Gay New York" makes a strong case that gay identity as it exists today emerged in the late nineteenth and early twentieth centuries as a mainly middle-class phenomenon, while U.S. working-class men continued until at least the 1940s to identify only "passive" malemale sexual behaviour with "fairies" and to consider men who played an "active" role in sexual intercourse with either women or men as "real men." 
If this same pattern held true for pre-war Central and Western Europe, it could explain many things. It could explain for example why self-identified gay men in Weimar Germany came largely from middle-class backgrounds and largely shared the conservative politics of their social class. It could also help explain why more left-leaning gay groups, like Magnus Hirschfeld’s Scientific-Humanitarian Committee, tended to put forward "old-fashioned" "third sex" theories, while a more "modern" approach was characteristic of more right-leaning groups like the Community of the Special.
All this is speculation. Although historians like John D’Emilio have already begun linking the social archaeology of emerging lesbian/gay communities in the post-war USA with the wellsprings of lesbian/gay politics,  similar work on the pre-war USA and Europe has not really begun. There is certainly plenty to study. Left-leaning "sex reformers" like Margaret Sanger, Emma Goldman, Crystal and Max Eastman and Floyd Dell in the United States and the Scientific-Humanitarian Committee in Holland were increasingly active in the 1910s, and networking internationally by the 1920s.
Studying sexual changes in the broader societies is difficult, given that almost everyone who was alive then is dead now. All the more reason why all possible sources should be sought out and the exploration begun.