Sexual communication with partners informs risk assessment and sexual practices. We evaluated participant, partner, and network factors associated with communication about condom use and HIV serostatus and explored their relationships with condomless anal intercourse (CAI) among 446 men who have sex with men (MSM) and 122 transgender women (TW) in Lima, Peru. Generalized estimating equations assessed contextual influences on communication and practices with recent sexual partners. MSM reported conversations about condom use before or during sex with 12.7% (163/1281) of partners and communicated about HIV serostatus with 15.3% (196/1285) of partners. They described CAI with 53.3% (681/1278) of these same partners. More frequent HIV communication was reported by MSM who: identified as heterosexual, compared to bisexual (aPR 0.35 [95% CI 0.15, 0.81], p-value 0.01) or gay (aPR 0.28 [95% CI 0.14, 0.59], p-value 0.001); characterized partnerships as stable, compared to casual (aPR 0.37 [95% CI 0.25, 0.54], p-value <0.001), anonymous (aPR 0.28 [95% CI 0.17, 0.46], p-value <0.001), or commercial (aPR 0.47 [95% CI 0.23, 0.98], p-value 0.04); or discussed HIV/STIs with close social contacts (aPR 2.18 [95% CI 1.19, 4.02], p-value 0.01). TW had conversations about condom use with 13.0% (45/347) of partners, communicated about HIV status with 16.9% (59/349), and reported CAI with 42.1% (146/347) of their previous three sexual partners. TW in concurrent partnerships discussed condom use more frequently than those in monogamous relationships (aPR 2.27 [95% CI 1.08, 4.77], p-value 0.03). Condom use discussions (aPR 1.20 [95% CI 1.04, 1.37], p-value 0.01) and alcohol use (aPR 1.15 [95% CI 1.03, 1.29], p-value 0.01) among MSM were associated with CAI. Findings highlight complexity in sexual decision-making and call for further study of conversation content and practices to inform HIV prevention messaging.