Submicron　chitosan/tripolyphosphate　(TPP)　particles　are　widely　investigated　as　nanocarriers　for　drugs,　genes　and　vaccines.　One　of　the　key　particle　properties　that　requires　control　is　their　size　distribution,　which　depends　on　the　extent　of　chitosan/TPP　primary　nanoparticle　aggregation　into　higher-order　submicron　colloids.　To　provide　a　better　understanding　of　this　higher-order　aggregation　process,　this　study　analyzes　the　factors　that　control　chitosan/TPP　particle　aggregation　kinetics　in　the　presence　of　free　TPP　(such　as　present　during　particle　formation).　The　aggregation　rates　exhibit　a　sharp　power-law　decrease　with　the　monovalent　salt　concentration　and　a　power-law　increase　with　the　free　TPP　concentration.　Moreover,　the　aggregation　rates　increase　with　the　pH　and　with　the　chitosan　degree　of　deacetylation　(DD).　These　variations　in　aggregation　rates　reflect　the　effects　of　monovalent　salt,　TPP　concentration,　pH　and　chitosan　DD　on　particle　bridging　by　the　surface-bound　TPP.　Furthermore,　these　aggregation　rates　are　much　faster　than　those　predicted　based　on　Derjaguin　and　Landau,　Verwey　and　Overbeek　(DLVO)　interaction　potentials,　which　might　reflect　nonuniformities　in　particle　shape　and　charge,　and/or　complications　caused　by　particle　softness.　Finally,　implications　of　the　above　aggregation　kinetics　on　the　uniformity　of　chitosan/TPP　micro-　and　nanogel　size　are　analyzed,　where　we:　(1)　show　how　particle　polydispersity　can　be　diminished　by　lowering　the　chitosan　DD;　and　(2)　explain　the　opposing　results　on　how　chitosan/TPP　particle　polydispersity　is　affected　by　monovalent　salt.　(C)　2016　Elsevier　Inc.　All　rights　reserved.