The Collaborative International Dictionary of English v.0.48:

Sociability \So`cia*bil"i*ty\, n.[Cf. F. sociabilit['e].]
   The quality of being sociable; sociableness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sociability
    n 1: the relative tendency or disposition to be sociable or
         associate with one's fellows [syn: sociability,
         sociableness] [ant: unsociability, unsociableness]

Moby Thesaurus II by Grady Ward, 1.0:

103 Moby Thesaurus words for "sociability":
   Bohemianism, accessibility, affability, amiability, amiableness,
   amicability, amicableness, amity, approachability, big mouth,
   candor, casualness, common touch, communicativeness, congeniality,
   conversableness, cordiality, correct deportment, courtesy,
   discourtesy, ease, easiness, easygoingness, effusion, effusiveness,
   etiquette, extroversion, familiarity, flow of words,
   flowing tongue, fluency, fluent tongue, flux de bouche,
   flux de paroles, flux of words, folksiness, frankness, freeness,
   friendliness, friendship, garrulity, garrulousness, gassiness,
   gift of gab, glibness, good behavior, good citizenship,
   good manners, graciousness, gregariousness, gush, gushiness,
   homeliness, homeyness, informality, informalness, irregularity,
   kindness, long-windedness, loose tongue, looseness, loquaciousness,
   loquacity, love, misbehavior, naturalness, neighborlikeness,
   neighborliness, offhandedness, openness, outgoingness,
   outspokenness, peaceableness, plainness, plainspokenness,
   poor behavior, prolixity, relaxedness, sanctioned behavior,
   simplicity, slush, spate of words, talkativeness, unaffectedness,
   unceremoniousness, unconstrainedness, unconstraint,
   unconventionality, unhostility, unpretentiousness, unrepression,
   unreserve, unreservedness, unrestraint, unrestriction, unreticence,
   unsecretiveness, unsuppression, untaciturnity, verbosity,
   volubility, well-affectedness, windiness