To serve global users safely and productively, LLMs need culture-specific knowledge that might not be learned during pre-training.How do we find knowledge that is (1) salient to ingroup users, but (2) unknown to LLMs?The most common solutions are single-initiative: either researchers define challenging questions that users passively answer (traditional annotation), or users actively produce data that researchers structure as benchmarks (knowledge extraction).The process would benefit from mixed-initiative collaboration, where users guide the process to meaningfully reflect their cultures, and LLMs steer the process to meet the researcher's goals.We propose CULTURE CARTOGRAPHY as a methodology that operationalizes this mixed-initiative vision.Here, an LLM initializes annotation with questions for which it has low-confidence answers, making explicit both its prior knowledge and the gaps therein.This allows a human respondent to fill these gaps and steer the model towards salient topics through direct edits.We implement CULTURE CARTOGRAPHY as a tool called CULTURE EXPLORER.Compared to a baseline where humans answer LLMproposed questions, we find that CULTURE EX-PLORER more effectively produces knowledge that strong models like DeepSeek R1, Llama-4 and GPT-4o are missing, even with web search.Fine-tuning on this data boosts the accuracy of Llama models by up to 19.2% on related culture benchmarks.

Cultural fit is widely believed to affect the success of individuals and the groups to which they belong.Yet it remains an elusive, poorly measured construct.Recent research draws on computational linguistics to measure cultural fit but overlooks asymmetries in cultural adaptation.By contrast, we develop a directed, dynamic measure of cultural fit based on linguistic alignment, which estimates the influence of one person's word use on another's and distinguishes between two enculturation mechanisms: internalization and selfregulation.We use this measure to trace employees' enculturation trajectories over a large, multi-year corpus of corporate emails and find that patterns of alignment in the first six months of employment are predictive of individuals downstream outcomes, especially involuntary exit.Further predictive analyses suggest referential alignment plays an overlooked role in linguistic alignment.